Answer:
dV/dt = 150.79 m^3/s
Explanation:
In order to calculate the rate of change of the volume, you calculate the derivative, respect to the radius of the sphere, of the volume of the sphere, as follow:
[tex]\frac{dV}{dt}=\frac{d}{dt}(\frac{4}{3}\pi r^3)[/tex] (1)
r: radius of the sphere
You calculate the derivative of the equation (1):
[tex]\frac{dV}{dt}=\frac{d}{dt}(\frac{4}{3}\pi r^3)=3\frac{4}{3}\pi r^2\frac{dr}{dt}=4\pi r^2\frac{dr}{dt}\\\\\frac{dV}{dt}=4\pi r^2\frac{dr}{dt}[/tex](2)
where dr/dt = 3m/s
You replace the values of dr/dt and r=2m in the equation (2):
[tex]\frac{dV}{dt}=4\pi (2m)^2(3\frac{m}{s})=150.79\frac{m^3}{s}[/tex]
The rate of change of the sphere, when it has a radius of 2m, is 150.79m^3/s
your washer has a power of 350 watts and your dryer has a power of 1800 watts how much energy do you use to clean a load of clothes in 1 hour of washing and 1 hour of drying?
A. 1.29 x 10^3 J
B. 2.58 x 10^3 J
C. 1.55 x 10^7 J
D. 7.74 x 10^6 J
Answer:
7.74 x 10⁶ Joules
Explanation:
recall that "Watts" is the SI unit used for "energy per unit time"
Hence "Watts" may also be expressed as Joules / Second (or J/s)
We are given that the washer is rated at 350W (i.e. 350 Joules / s) and the dryer is rated at 1800W (i.e. 1800 Joules / s).
We are also given that the appliances are each run for 1 hour
1 hour = 60 min = (60 x 60) seconds = 3600 seconds
Hence the total energy used,
= Energy used by Washer in 1 hour + Energy used by dryer in 1 hour
= (350 J/s x 3600 s) + (1800 J/s x 3600 s)
= 3600 ( 350 + 1800)
= 3600 (2150)
= 7,740,000 Joules
= 7.74 x 10⁶ Joules
A 1.20 kg water balloon will break if it experiences more than 530 N of force. Your 'friend' whips the water balloon toward you at 13.0 m/s. The maximum force you apply in catching the water balloon is twice the average force. How long must the interaction time of your catch be to make sure the water balloon doesn't soak you
Answer:
t = 0.029s
Explanation:
In order to calculate the interaction time at the moment of catching the ball, you take into account that the force exerted on an object is also given by the change, on time, of its linear momentum:
[tex]F=\frac{\Delta p}{\Delta t}=m\frac{\Delta v}{\Delta t}[/tex] (1)
m: mass of the water balloon = 1.20kg
Δv: change in the speed of the balloon = v2 - v1
v2: final speed = 0m/s (the balloon stops in my hands)
v1: initial speed = 13.0m/s
Δt: interaction time = ?
The water balloon brakes if the force is more than 530N. You solve the equation (1) for Δt and replace the values of the other parameters:
[tex]|F|=|530N|= |m\frac{v_2-v_1}{\Delta t}|\\\\|530N|=| (1.20kg)\frac{0m/s-13.0m/s}{\Delta t}|\\\\\Delta t=0.029s[/tex]
The interaction time to avoid that the water balloon breaks is 0.029s
In this problem we will consider the collision of two cars initially moving at right angles. We assume that after the collision the cars stick together and travel off as a single unit. The collision is therefore completely inelastic. Two cars of masses m1 and m2 collide at an intersection. Before the collision, car 1 was traveling eastward at a speed of v1, and car 2 was traveling northward at a speed of v2. After the collision, the two cars stick together and travel off in the direction.
Required:
a. Write the momentum conservation equation for the east-west components.
b. Write the momentum conservation equation for the north-south components.
c. Find the tangent of the angle.
Answer:
a) vfₓ = m₁ / (m₁ + m₂) v₁, b) tan θ = m₂ / m₁ v₂ / v₁, c)
Explanation:
Momentum is a vector quantity, so the consideration must be fulfilled in all axes
a) conservation of the moment east-west direction
the system is formed by the two cases, so that the forces during the sackcloth have been internal and therefore the mummer remains
before the crash
p₀ = m₁ v₁
after the crash
[tex]p_{f}[/tex]= (m1 + m2) vfₓ
p₀ = pf
m₁ v₁ = (m₁ + m₂) vfₓ
vfₓ = m₁ / (m₁ + m₂) v₁
b) conservation of the North-South axis moment
before the shock
p₀ = m₂ v₂
after the crash
p_{f} = ( m₁ +m₂) [tex]vf_{y}[/tex]
p₀ = p_{f}
me 2 v₂ = (m₁ + m₂) vfy
[tex]vf_{y}[/tex] = m₂ / (m₁ + m₂) v₂
c) the angle with which the car moves is
tan θ = Vfy / Vfₓ
tan θ = [m₂ / (m₁ + m₂) v] / [m₁ / (m₁ + m₂) v₁]
tan θ = m₂ / m₁ v₂ / v₁
The momentum conservation equation for the north-south components is [tex]m_1u_1 = v(m_1 + m_2)[/tex]
The momentum conservation equation for the north-south components is [tex]m_2u_2 = v(m_1 + m_2)[/tex]
The tangent of the angle is 1.
The given parameters;
angle between the initial velocity of the cars, θ = 90Apply the principle of conservation of linear momentum of inelastic collision as shown below;
[tex]m_1u_1 + m_2u_2 = v(m_1 + m_2)[/tex]
The momentum conservation equation for the east-west components is written as follows;
[tex]m_1(u_1cos \ 0) + m_2(u_2 cos 90)= v(m_1 + m_2)\\\\m_1u_1 = v(m_1 + m_2)[/tex]
The momentum conservation equation for the north-south components is written as follows;
[tex]m_1(u_1sin 0) + m_2(u_2sin90) = v(m_1 + m_2)\\\\m_2u_2 = v(m_1 + m_2)[/tex]
The tangent of the angle is calculated as follows;
[tex]tan \ \theta = \frac{p_y}{p_x} = \frac{v(m_1 + m_2)}{v(m_1 + m_2)} \\\\tan \ \theta = 1\\\\\theta = tan^{-1} (1) \\\\\theta = 45\ ^0[/tex]
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Two identical pendulums have the same period when measured in the factory. While one pendulum swings on earth, the other is taken on a spaceship traveling at 95%% the speed of light. Assume that both pendulums operate under the influence of the same net force and swing through the same angle.
When observed from earth, how many oscillations does the pendulum on the spaceship undergo compared to the pendulum on earth in a given time interval?
a. more oscillations
b. fewer oscillations
c. the same number of oscillations
Answer:
Explanation:
As a result of impact of time widening, a clock moving as for an observer seems to run all the more gradually than a clock that is very still in the observer's casing.
At the point when observed from earth, the pendulum on the spaceship takes more time to finish one oscillation.
Hence, the clock related with that pendulum will run more slow (gives fewer oscillations as observed from the earth) than the clock related with the pendulum on earth.
Ans => B fewer oscillations
What is the work done in stretching a spring by a distance of 0.5 m if the restoring force is 24N?
Answer:
3Nm
Explanation:
work = 0.5 x 12 x 0.5 = 3
The work done in stretching the spring by a distance of 0.5 m, with a restoring force of 24 N, is 6 joules.
To calculate the work done in stretching a spring, we can use the formula for work done by a spring:
Work = (1/2) * k *[tex]x^2[/tex]
where:
k = spring constant
x = distance the spring is stretched
Given that the restoring force (F) acting on the spring is 24 N, and the distance the spring is stretched (x) is 0.5 m, we can find the spring constant (k) using Hooke's law:
F = k * x
k = F / x
k = 24 N / 0.5 m
k = 48 N/m
Now, we can calculate the work:
Work = (1/2) * 48 N/m * [tex](0.5 m)^2[/tex]
Work = (1/2) * 48 N/m * [tex]0.25 m^2[/tex]
Work = 6 joules
Therefore, the work done in stretching the spring by a distance of 0.5 m, with a restoring force of 24 N, is 6 joules.
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2. A 2.0-kg block slides down an incline surface from point A to point B. Points A and B are 2.0 m apart. If the coefficient of kinetic friction is 0.26 and the block is starting at rest from point A. What is the work done by friction force
Answer:a
Explanation:
How can global warming lead to changes to the Earth’s surface? a. Global warming can lead to an increased number of earthquakes, which change the Earth’s surface. b. Global warming can lead to glaciers melting, causing flooding to areas and the decrease of glacial land masses. c. Global warming leads to a decrease in water levels of coastal wetlands. d. Global warming cannot lead to changes to the Earth’s surface.
Answer:
Option: b. Global warming can lead to glaciers melting, causing flooding to areas and the decrease of glacial land masses.
Explanation:
Global warming is the reason for the changes in environment and climate on earth. Melting of glaciers leads to an increase in water level and a decrease in landmass. One of the most climactic consequences is the decrease in Arctic sea ice. Melting polar ice along with ice sheets and glaciers across Greenland, North America, Europe, Asia, and South America suspected to increase sea levels slowly. There is an increase in the glacial retreat due to global warming, which leaves rock piles that covered with ice.
Answer:
B: Global warming can lead to glaciers melting, causing flooding to areas and the decrease of glacial land masses.
Explanation:
Global warming is primarily caused by the increase in greenhouse gases, such as carbon dioxide, in the Earth's atmosphere. This leads to a rise in global temperatures, which has various impacts on the Earth's surface. One significant effect is the melting of glaciers and ice caps in polar regions and mountainous areas.
As temperatures increase, glaciers and ice sheets start to melt at a faster rate. This melting results in the release of massive amounts of water into rivers, lakes, and oceans. Consequently, there can be an increase in the frequency and intensity of flooding events in regions downstream from these melting glaciers.
Moreover, the melting of glaciers and ice caps contributes to a rise in sea levels. As the melted ice enters the oceans, it adds to the overall volume of water, leading to a gradual increase in sea levels worldwide. This rise in sea levels poses a threat to coastal areas, as they become more vulnerable to coastal erosion, storm surges, and saltwater intrusion into freshwater sources.
Additionally, the loss of glacial land masses due to melting can have long-term effects on ecosystems. Glaciers act as freshwater reservoirs, releasing water gradually throughout the year. With their decline, the availability of freshwater for agriculture, drinking water, and other human needs can be significantly affected.
Therefore, global warming can indeed lead to changes in the Earth's surface, particularly through the melting of glaciers and subsequent impacts on sea levels, flooding, and glacial land masses.
E23 verified.
A soap bubble of radius R is situated in a uniform electric field of magnitude E. The electric flux through the surface of the soap bubble is
Answer:
The electric flux around the soap bubble will be
Ф = q/ε
Explanation:
The radius of the soap bubble = R
The electric field around the soap bubble = E
The electric flux = ?
The soap can be approximated to be a sphere, so we find the surface area of the sphere
For the soap bubble, the surface area will be
A = [tex]4\pi R^{2}[/tex]
Recall that electric flux is given as
Ф = EA
substituting value of A from above, we'll have
Ф = E[tex]4\pi R^{2}[/tex]..... equ 1
Also recall that the electric field E is given as
E = q/(4πε[tex]R^{2}[/tex])
substitute the value of E into equ 1, to get
Ф = q/(4πε[tex]R^{2}[/tex]) * [tex]4\pi R^{2}[/tex]
The electric flux around the soap bubble reduces to
Ф = q/ε
Two lenses of focal length 4.5cm and 1.5cm are placed at a certain distance apart, calculate the distance between the lenses if they form an achromatic combination
3.0cm
Explanation:
For lenses in an achromatic combination, the following condition holds, assuming the two lenses are of the same materials;
d = [tex]\frac{f_1 + f_2}{2}[/tex] ---------(i)
Where;
d= distance between lenses
f₁ = focal length of the first lens
f₂ = focal length of the second lens
From the question;
f₁ = 4.5cm
f₂ = 1.5cm
Substitute these values into equation (i) as follows;
d = [tex]\frac{4.5+1.5}{2}[/tex]
d = [tex]\frac{6.0}{2}[/tex]
d = 3.0cm
Therefore, the distance between the two lenses is 3.0cm
A beam of light is propagating in the x direction. The electric-field vector Group of answer choices can oscillate in any arbitrary direction in space. must oscillate in the z direction. must oscillate in the yz plane. must oscillate in the x direction. must have a steady component in the x direction.
Answer:
Option C is correct.
The electric-field vector must oscillate in the yz plane.
Explanation:
Light, in waveform, is an electromagnetic wave.
And electromagnetic waves are known to have their electric and magnetic field perpendicular to each other and also simultaneously perpendicular to the direction of propagation of the wave.
If the velocity of direction of propagation of the wave is in one direction, the electric-field vector must be in a direction we are sure is perpendicular to this direction of wave propagation and the wave's magnetic field.
Of the options provided, only option B (z-direction) and option C (yz-plane) show a direction that is indeed perpendicular to the direction of propagation of the wave (x-axis).
And truly, the electric-field vector for this wave can be in any of the two directions without breaking the laws of physics, but the electric-field vector oscillating in the yz-plane is a more general answer as it covers all the possible directions that the electric-field can oscillate in, including the one specified by option B (z-direction).
Hence, the correct answer is option C.
Hope this Helps!!!
What direct current will produce the same amount of thermal energy, in a particular resistor, as an alternating current that has a maximum value of 2.59 A?
Answer:
The direct current that will produce the same amount of thermal energy is 1.83 A
Explanation:
Given;
maximum current, I₀ = 2.59 A
The average power dissipated in a resistor connected in an AC source is given as;
[tex]P_{avg} = I_{rms} ^2R[/tex]
Where;
[tex]I_{rms} = \frac{I_o}{\sqrt{2} }[/tex]
[tex]P_{avg} = (\frac{I_o}{\sqrt{2} } )^2R\\\\P_{avg} = \frac{I_o^2R}{2} ----equation(1)[/tex]
The average power dissipated in a resistor connected in a DC source is given as;
[tex]P_{avg} = I_d^2R --------equation(2)[/tex]
where;
[tex]I_d[/tex] is direct current
Solve equation (1) and (2) together;
[tex]I_d^2R = \frac{I_o^2R}{2} \\\\I_d^2 = \frac{I_o^2}{2} \\\\I_d=\sqrt{\frac{I_o^2}{2} } \\\\I_d = \frac{I_o}{\sqrt{2}} \\\\I_d = \frac{2.59}{\sqrt{2} } \\\\I_d = 1.83 \ A[/tex]
Therefore, the direct current that will produce the same amount of thermal energy is 1.83 A
Changing the camber of a wing by designing positive curvature in or lowering trailing edge flaps allows:______.
A. Higher Maximum Coefficients of Lift
B. Maximum Coefficient of Lift at lower Angle of Attack
C. Lower landing/approach angles of attack
D. A and C
E. All of the above
Answer:
E. All of the above
Explanation:
The wings that contain curvature is known as "camber," which in essence is half of a venturi, generating a greater-pressure area at the bottom of the wing, and a lesser-pressure area at the top. Creating an extra lift, the camber (curvature) of the wing is increased by extending (in an arc) the leading edge, typically by forcing or hinging the leading edge out on tracks.
The additional camber provides them with the additional lift needed for safe operation and control at slower aircraft speeds, such as when departing or landing.
By allowing wings to operate at a greater angle. A high lift coefficient is established and used as an angle of element for both attack and speed, when an airplane can travel extra steadily or take off and land in a smaller time with slats
Therefore the correct option is E.
Your 64-cm-diameter car tire is rotating at 3.4 rev/s when suddenly you press down hard on the accelerator. After traveling 260 m, the tire's rotation has increased to 5.5 rev/s.
What is the tires angular acceleration?
Answer:
The angular acceleration of the tire is 0.454 rad/s²
Explanation:
Given;
initial velocity, u = 3.4 rev/s = 3.4 rev/s x 2π rad/rev
u = 21.3656 rad/sec
final velocity, v = 5.5 rev/s = 5.5 rev/s x 2π rad/rev
v = 34.562 rad/sec
Calculate the value of angular rotation, θ, of the tire
θ = Number of revolutions x 2π rad/rev
θ = [tex]\frac{260}{2 \pi r} *\frac{2 \pi \ rad}{rev}[/tex]
θ = (260 / r)
r is the radius of the tire = 64 / 2 = 32cm = 0.32 m
θ = (260 / 0.32)
θ = 812.5 rad
Apply the following kinematic equation, to determine angular acceleration of the tire;
[tex]v^2 = u^2 + 2 \alpha \theta\\\\2 \alpha \theta = v^2 - u^2\\\\\alpha = \frac{v^2-u^2}{2 \theta} \\\\\alpha = \frac{(34.562)^2-(21.3656)^2}{2 (812.5)}\\\\\alpha = \frac{738.043}{1625} \\\\\alpha = 0.454 \ rad/s^2[/tex]
Therefore, the angular acceleration of the tire is 0.454 rad/s²
A rod of very small diameter with a mass 2m and length 3L is placed along the xaxis with one end at the origin. An identical rod is placed along the yaxis with one end at the origin, so that the two rods form an L-shape. What are the coordinates of the center of mass for these two rods
Answer:
coordinates of the center of mass for these two rods
([tex]x_{cm}[/tex], [tex]y_{cm}[/tex])= ([tex]\frac{3L}{4}[/tex], [tex]\frac{3L}{4}[/tex])cm
Explanation:
given
mass of a rod = 2m
length of the rod = 3L
mass of two rods = 2(2m) = 4m
radius = diameter/2 = [tex]\frac{3L}{2}[/tex]
attached is the diagram and solution to the question
A spring with a 3.15kg weight hanging from it measures 13.40cm, and without the weight 12.00cm. If you hang a weight on it so as to store 10.0J potential energy in it, how long will the spring be?
Answer:
21.52 cm
Explanation:
Given that
mass of the spring, m = 3.15 kg
Length of the spring l2, = 13.4 cm = 0.134 m
Length of the spring l1 = 12 cm = 0.12 m
change in extension, x = 0.134 - 0.12 = 0.014 m
Acceleration due to gravity, g = 9.8 m/s²
Potential Energy, U = 10 J
See attachment for calculation
Answer:
Final Length = 12.45 cm
Explanation:
First we need to find the spring constant. From Hooke's Law:
F = kΔx
where,
F = Force Applied on Spring = Weight = mg = (3.15 kg)(9.8 m/s²) = 30.87 N
k = spring constant = ?
Δx = change in length of spring = 13.4 cm - 12 cm = 1.4 cm = 0.014 m
Therefore,
30.87 N = k(0.014 m)
k = (30.87 N)/(0.014 m)
k = 2205 N/m
Now, for the Potential Energy of 10 J:
P.E = (1/2)KΔx²
where,
P.E = Potential Energy of Spring = 10 J
Δx = ?
Therefore,
10 J = (2205 N/m)Δx²
Δx = √[10 J/(2205 N/m)
Δx = Final Length - Initial length = 0.0045 m = 0.45 cm
Final Length = 0.45 cm + 12 cm
Final Length = 12.45 cm
A typical arteriole has a diameter of 0.080 mm and carries blood at the rate of 9.6 x10-5 cm3/s. What is the speed of the blood in (cm/s) the arteriole
Answer:
v= 4.823 × 10⁻⁹ cm/s
Explanation:
given
flow rate = 9.6 x10-5 cm³/s, d = 0.080mm
r = d/2= 0.080/2= 0.0040 cm
speed = rate of blood flow × area
v = (9.6 x 10⁻⁵ cm³/s) × (πr²)
v = (9.6 x 10⁻⁵ cm³/s) × π(0.0040 × cm)²
v= 1.536 × 10⁻⁹π cm/s
v= 4.823 × 10⁻⁹ cm/s
A proton with an initial speed of 400000 m/s is brought to rest by an electric field.
Part A- Did the proton move into a region of higher potential or lower potential?
Part B - What was the potential difference that stopped the proton?
?U = ________V
Part C - What was the initial kinetic energy of the proton, in electron volts?
Ki =_________eV
Answer:
moves into a region of higher potential
Potential difference = 835 V
Ki = 835 eV
Explanation:
given data
initial speed = 400000 m/s
solution
when proton moves against a electric field so that it will move into higher potential region
and
we know Work done by electricfield W is express as
W = KE of proton K
so
q × V = 0.5 × m × v² ......................1
put here va lue
1.6 × [tex]10^{-19}[/tex] × V = 0.5 × 1.67 × [tex]10^{-27}[/tex] × 400000²
Potential difference V = 1.336 × 10-16 / 1.6 × 10-19
Potential difference = 835 V
and
KE of proton in eV is express as
Ki = V numerical
Ki = 835 eV
Find the terminal velocity (in m/s) of a spherical bacterium (diameter 1.81 µm) falling in water. You will first need to note that the drag force is equal to the weight at terminal velocity. Take the density of the bacterium to be 1.10 ✕ 103 kg/m3. (Assume the viscosity of water is 1.002 ✕ 10−3 kg/(m · s).)
Answer:
The terminal velocity of a spherical bacterium falling in the water is 1.96x10⁻⁶ m/s.
Explanation:
The terminal velocity of the bacterium can be calculated using the following equation:
[tex] F = 6\pi*\eta*rv [/tex] (1)
Where:
F: is drag force equal to the weight
η: is the viscosity = 1.002x10⁻³ kg/(m*s)
r: is the radium of the bacterium = d/2 = 1.81 μm/2 = 0.905 μm
v: is the terminal velocity
Since that F = mg and by solving equation (1) for v we have:
[tex] v = \frac{mg}{6\pi*\eta*r} [/tex]
We can find the mass as follows:
[tex] \rho = \frac{m}{V} \rightarrow m = \rho*V [/tex]
Where:
ρ: is the density of the bacterium = 1.10x10³ kg/m³
V: is the volume of the spherical bacterium
[tex] m = \rho*V = \rho*\frac{4}{3}\pi*r^{3} = 1.10 \cdot 10^{3} kg/m^{3}*\frac{4}{3}\pi*(0.905 \cdot 10^{-6} m)^{3} = 3.42 \cdot 10^{-15} kg [/tex]
Now, the terminal velocity of the bacterium is:
[tex] v = \frac{mg}{6\pi*\eta*r} = \frac{3.42 \cdot 10^{-15} kg*9.81 m/s^{2}}{6\pi*1.002 \cdot 10^{-3} kg/(m*s)*0.905 \cdot 10^{-6} m} = 1.96 \cdot 10^{-6} m/s [/tex]
Therefore, the terminal velocity of a spherical bacterium falling in the water is 1.96x10⁻⁶ m/s.
I hope it helps you!
3. A body moves along a semicircular path. The ratio of distance to displacement is
Answer:
Ratio of distance to displacement is pi/2
Explanation:
Pls see attached file for diagram and explanation
Blue light (λ = 475 nm) is sent through a single slit with a width of 2.1 µm. What is the maximum possible number of bright fringes, including the central maximum, produced on the screen? (Hint: What is the largest angle that can be used?)
Answer:
m = 4
Explanation:
The expression that explains the constructive interference of a diffraction pattern is
a sin θ = m λ
where a is the width of the slit and λ the wavelength
sin θ = m λ / a
The maximum value is for when the sine is 1, let's substitute
1 = m λ/a
m = a /λ
let's reduce the magnitudes to the SI system
a = 2.1 um = 2.1 10⁻⁶
lam = 475 nm = 475 10⁻⁹ m
let's calculate
m = 2.1 10⁻⁶ / 475 10⁻⁹
m = 4.42
with m must be an integer the highest value is
m = 4
The spectral lines of two stars in a particular eclipsing binary system shift back and forth with a period of 3 months. The lines of both stars shift by equal amounts, and the amount of the Doppler shift indicates that each star has an orbital speed of 88,000 m/s. What are the masses of the two stars
Answer:
Explanation:
given
T = 3months = 7.9 × 10⁶s
orbital speed = 88 × 10³m/s
V= 2πr÷T
∴ r = (V×T) ÷ 2π
r = (88km × 7.9 × 10⁶s) ÷ 2π
r = 1.10 × 10⁸km
using kepler's 3rd law
mass of both stars = (seperation diatance)³/(orbital speed)²
M₁ + M₂ = (2r)³/([tex]\frac{1}{4}[/tex]year)²
= (1.06 × 10²⁵)/(6.2×10¹³)
1.71×10¹²kg
since M₁ = M₂ =1.71×10¹²kg ÷ 2
M₁ = M₂ = 8.55×10¹¹kg
Which of the following gives the magnitude of the average velocity (over the entire run) of an athlete running on a circular track with a circumference of 0.5 km, if that athlete runs a total length of 1.0 km in a time interval of 4 minutes?
a. O m/s
b. 2 m/s
c. 4.2 m/s
d. 16.8 m/s
Answer:
c. 4.2 m/s
Explanation:
The definition of the average velocity, measured in meters per second, is given by the following expression:
[tex]\bar v = \frac{x_{f}-x_{o}}{t_{f}-t_{o}}[/tex]
Where:
[tex]x_{o}[/tex], [tex]x_{f}[/tex] - Initial and final positions, measured in meters.
[tex]t_{o}[/tex], [tex]t_{f}[/tex] - Initial and final instants, measured in seconds.
Positions and instants must be written in meters and seconds, respectively:
[tex]x_{o} = 0\,m[/tex], [tex]x_{f} = 1000\,m[/tex].
[tex]t_{o} = 0\,s[/tex], [tex]t_{f} = 240\,s[/tex].
Finally, the average velocity of the athlete that runs a total length of 1.0 kilometer in a time interval of 4 minutes is:
[tex]\bar v = \frac{1000\,m-0\,m}{240\,s-0\,s}[/tex]
[tex]\bar v = 4.167\,\frac{m}{s}[/tex]
Hence, the best option is C.
A 150 V battery is connected across two parallel metal plates of area 28.5 cm2 and separation 0.00820 m. A beam of alpha particles (charge +2e, mass 6.64Ã10â27 kg) is accelerated from rest through a potential difference of 1.75 kV and enters the region between the plates perpendicular to the electric field.What magnitude and direction of magnetic field are needed so that the alpha particles emerge undeflected from between the plates?
Answer:
B = 4.45mT in the +^k direction
Explanation:
In order to calculate the required magnitude of the magnetic force, to achieve that the beam of particles emerge undeflected of the parallel plates, the electric force between the plates and the magnetic field in that region must be equal.
[tex]F_E=F_B\\\\qE=qvB[/tex] (1)
q: charge of the particles beam = +2e = 2*1.6*10^-19C
v: speed of the particles = ?
B: magnitude of the magnetic field = ?
E: electric field between the plates = V/d
V: potential difference between the parallel plates = 150V
d: distance of separation of the plates = 0.00820m
If you assume that the below plate is negative, the electric force on the particles has a direction upward (+^j). Then, the direction of the magnetic force must be downwards (-^j).
To obtain a downward magnetic force, it is necessary that the magnetic field point out of the page. In fact, if the direction of motion of the particles is toward east (+^i) and the magnetic field points out of the page (+^k), you have:
^i X ^k = -^j
Furthermore, it is necessary to calculate the sped of the particles. It is made by using the information about the charge, the potential difference that accelerates the particles and the kinetic energy.
[tex]K=qV=\frac{1}{2}mv^2\\\\v=\sqrt{\frac{2qV}{m}}[/tex] (2)
You replace the expression (2) into the equation (1) and solve for B:
[tex]B=\frac{E}{v}=E\sqrt{\frac{m}{2qV}}[/tex]
[tex]B=\frac{V}{d}\sqrt{\frac{m}{2qV}}\\\\B=\frac{150V}{0.0820m}\sqrt{\frac{6.64*10^{-27}kg}{2(2(1,6*10^{-19}C))(1.75*10^3V)}}\\\\B=4.45*10^{-3}T=4.45mT[/tex]
The required magnitude of the magnetic field is 4.45mT and has a direction out of the page +^k
Following are the solution to the given question:
In order to emerge using reflecting means, use the following formula:
[tex]\to F_E = F_B ..............(1)\\\\ \to F_E = \text{electric force}\\\\ \to F_B = \text{magnetic force}\\\\[/tex]
Calculating the Lorent's force:
[tex]\to F=qE+qv \times B \ \ also,\ \ K_{E} =U_{E} \\\\[/tex]
[tex]\to K_{E}[/tex][tex]= \text{kinetic energy} = -\frac{1}{2} \ mv^2 \\\\[/tex]
[tex]\to U_{E} = \text{potential energy} = q_V[/tex]
Calculating the value of v: \\\\
[tex]\to v= \sqrt{\frac{2qV}{m}} \\\\ \to q = 2e^{+} = 2 (1.6 \times 10^{-19}\ C) = 3.2 \times 10^{-19} C \\\\\to V = 1.75 \times 10^{3} \V \\\\\to m = 6.64 \times 10^{-27} \ kg\\\\ \to v = 410,700.25 \ \frac{m}{s}\\\\[/tex]
It's the particle's velocity, but the velocity also is defined as:
[tex]\to v=\frac{E}{B}[/tex]
solving for B:
[tex]\to B= \frac{E}{v}\\\\[/tex]
[tex]= \frac{\frac{V}{d}}{v}\\\\ =\frac{V}{vd} \\\\= \frac{150\ V}{(410,700.25 \ \frac{m}{s}) (8.2 \times 10^{-3} m)} \\\\= 0.045\ T\\\\[/tex]
When indicated in the diagram, the direction is parallel to "v" and E.
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Does there appear to be a simple mathematical relationship between the acceleration of an object (with fixed mass and negligible friction) and the force applied to the object (measured by the force probe mounted on the object)? Describe the mathematical relationship in words.
Answer:
the net force applied to an object is directly proportional to the acceleration undergone by that object
Explanation:
This verbal statement can be expressed in equation form as follows:
a = Fnet / m
You are a passenger in a car and not wearing your seat belt. Without increasing or decreasing its speed, the car makes a sharp left turn, and you find yourself colliding with the right-hand door. Which is the correct analysis of the situation?a. During the turn, there is a rightward force pushing you into the door. b. During the turn, the door exerts a leftward force on you. c. both of the above. d. neither of the above
Answer:
b) During the turn, the door exerts a leftward force on you.
Explanation:
Although at the curve the car makes a turn without deceleration or accelerating, we must consider the fact that the direction of the instantaneous velocity of the car, which is always pointing tangentially away from the curve, is changing, producing a centripetal acceleration (acceleration is the rate of change of velocity) towards the center of the curve. The result is that a force inwards towards the center of the curve from the door, is exerted on you in the leftwards direction when your body collides with the door.
A loop of wire with cross-sectional area 1 m2 is inserted into a uniform magnetic field with initial strength 1 T. The field is parallel to the axis of the loop. The field begins to grow with time at a rate of 2 Teslas per hour. What is the magnitude of the induced EMF in the loop of wire
Answer:
The magnitude of the EMF is 0.00055 volts
Explanation:
The induced EMF is proportional to the change in magnetic flux based on Faraday's law:
[tex]emf\,=-\,N\, \frac{d\Phi}{dt}[/tex]
Since in our case there is only one loop of wire, then N=1 and we get:
[tex]emf\,=-\,N\, \frac{d\Phi}{dt}[/tex]
We need to express the magnetic flux given the geometry of the problem;
[tex]\Phi=B\,\,A[/tex]where A is the area of the coil that remains unchanged with time, and B is the magnetic field that does change with time. Therefore the equation for the EMF becomes:
[tex]emf\,=-\,N\, \frac{d\Phi}{dt} = \frac{d\Phi}{dt} =-\frac{d\,(B\,A)}{dt} =-\,A\,\frac{d\,(B)}{dt}=- 1\,m^2(2\,\,T/h})= -2\,\,m^2\,T/(3600\,\,s)= -0.00055\,Volts[/tex]
An infinitely long line of charge with uniform density, rho???????? lies in y-z plane parallel to the zaxis at y=1m. (a) Find the potential VAB at point A (4m, 2m, 4m) in Cartesian coordinates with respect to point B (0,0,0). (b) Find E filed at point B.
Answer with Explanation:
We are given that
Density=[tex]\rho l[/tex]
A(4m,2m,4m) and B(0,0,0)
y=1 m
a. Linear charge density=[tex]\frac{\rho l}{l}=\rho C/m[/tex]
Let a point P (0,1,4) on the line of charge and point Q (0,1,0)
Therefore,
Distance AP=[tex]\sqrt{(4-0)^2+(2-1)^2+(4-4)^2}=\sqrt{17}[/tex]
Distance,BQ=[tex]\sqrt{(0-0)^2+(1-0)^2+(0-0)^2}=1[/tex]
Electric field for infinitely long line
[tex]E=\frac{\rho}{2\pi \epsilon_0 r}\cdot \hat{r}[/tex]
Therefore, potential
[tex]V_{BA}=-\int_{a}^{b}E\cdot dl[/tex]
[tex]V_{BA}=-\int_{\sqrt{17}}^{1}\frac{\rho}{2\pi \epsilon_0 r}\hat{r}\cdot \hat{r} dr[/tex]
[tex]V_{BA}=-\int_{\sqrt{17}}^{1}\frac{\rho}{2\pi \epsilon_0 r}dr[/tex]
[tex]V_{BA}=-\frac{\rho}{2\pi \epsilon_0}[\ln r]^{1}_{\sqrt{17}}[/tex]
[tex]V_{BA}=-\frac{\rho}{2\pi \epsilon_0}(ln 1-ln(\sqrt{17})=\frac{\rho}{2\pi \epsilon_0}(ln(\sqrt{17})[/tex]
[tex]V_{BA}=V_B-V_A[/tex]
[tex]V_{AB}=V_A-V_B=-V_{BA}=-\frac{\rho}{2\pi \epsilon_0}(ln(\sqrt{17})[/tex]
b.Electric field at point B
[tex]E=\frac{\rho}{2\pi \epsilon_0 r}\cdot \hat{r}[/tex]
Unit vector r=[tex]-\hat{j}[/tex]
Therefore,
[tex]E=\frac{\rho}{2\pi \epsilon_0 r}\cdot \hat{-j}[/tex]
A water-balloon launcher with mass 5 kg fires a 1 kg balloon with a velocity of
8 m/s to the east. What is the recoil velocity of the launcher?
Answer:
1.6 m/s west
Explanation:
The recoil velocity of the launcher is 1.6 m/s west.
What is conservation of momentum principle?When two bodies of different masses move together each other and have head on collision, they travel to same or different direction after collision.
A water-balloon launcher with mass 5 kg fires a 1 kg balloon with a velocity of 8 m/s to the east.
Final momentum will be zero, so
m₁u₁ +m₂u₂ =0
Substitute the values for m₁ = 5kg, m₂ =1kg and u₂ =8 m/s, then the recoil velocity will be
5 x v +1x8 = 0
v = - 1.6 m/s
Thus, the recoil velocity of the launcher is 1.6 m/s (West)
Learn more about conservation of momentum principle
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When a hydrometer (see Fig. 2) having a stem diameter of 0.30 in. is placed in water, the stem protrudes 3.15 in. above the water surface. If the water is replaced with a liquid having a specific gravity of 1.10, how much of the stem would protrude above the liquid surface
Answer:
5.79 in
Explanation:
We are given that
Diameter,d=0.30 in
Radius,r=[tex]\frac{d}{2}=\frac{0.30}{2}=0.15 in[/tex]
Weight of hydrometer,W=0.042 lb
Specific gravity(SG)=1.10
Height of stem from the water surface=3.15 in
Density of water=[tex]62.4lb/ft^3[/tex]
In water
Volume of water displaced [tex]V=\frac{mass}{density}=\frac{0.042}{62.4}=6.73\times 10^{-4} ft^3[/tex]
Volume of another liquid displaced=[tex]V'=\frac{V}{SG}=\frac{6.73\times 10^{-4}}{1.19}=5.66\times 10^{-4}ft^3[/tex]
Change in volume=V-V'
[tex]V-V'=\pi r^2 l[/tex]
Substitute the values
[tex]6.73\times 10^{-4}-5.66\times 10^{-4}=3.14\times (\frac{0.15}{12})^2l[/tex]
By using
1 ft=12 in
[tex]\pi=3.14[/tex]
[tex]l=\frac{6.73\times 10^{-4}-5.66\times 10^{-4}}{3.14\times (\frac{0.15}{12})^2}[/tex]
l=2.64 in
Total height=h+l=3.15+2.64= 5.79 in
Hence, the height of the stem protrude above the liquid surface=5.79 in
A 40.0 kg ballet dancer stands on her toes during a performance with 25.0 cm2 in contact with the floor. What is the pressure exerted by the floor over the area of contact if the dancer is stationary
Explanation:
40×10ms^-2
400N.
25/100m^2
0.25m^2
1.P=F/A
=400N/0.25m^2
=100Nm^-2
=100Pa