Answer:
A) v₁ = 10.1 m/s t₁= 4.0 s
B) x₂= 17.2 m
C) v₂=7.1 m/s
D) x₂=7.5 m
Explanation:
A)
Assuming no friction, total mechanical energy must keep constant, so the following is always true:[tex]\Delta K + \Delta U = (K_{f} - K_{o}) +( U_{f} - U_{o}) = 0 (1)[/tex]
Choosing the ground level as our zero reference level, Uf =0.Since the child starts from rest, K₀ = 0.From (1), ΔU becomes:[tex]\Delta U = 0- m*g*h = -m*g*h (2)[/tex] In the same way, ΔK becomes:[tex]\Delta K = \frac{1}{2}*m*v_{1}^{2} (3)[/tex] Replacing (2) and (3) in (1), and simplifying, we get:[tex]\frac{1}{2}*v_{1}^{2} = g*h (4)[/tex]
In order to find v₁, we need first to find h, the height of the slide.From the definition of sine of an angle, taking the slide as a right triangle, we can find the height h, knowing the distance that the child slides down the slope, x₁, as follows:[tex]h = x_{1} * sin \theta_{1} = 20.0 m * sin 15 = 5.2 m (5)[/tex]
Replacing (5) in (4) and solving for v₁, we get:
[tex]v_{1} = \sqrt{2*g*h} = \sqrt{2*9.8m/s2*5.2m} = 10.1 m/s (6)[/tex]
As this speed is achieved when all the energy is kinetic, i.e. at the bottom of the first slide, this is the answer we were looking for.Now, in order to finish A) we need to find the time that the child used to reach to that point, since she started to slide at the its top.We can do this in more than one way, but a very simple one is using kinematic equations.If we assume that the acceleration is constant (which is true due the child is only accelerated by gravity), we can use the following equation:[tex]v_{1}^{2} - v_{o}^{2} = 2*a* x_{1} (7)[/tex]
Since v₀ = 0 (the child starts from rest) we can solve for a:[tex]a = \frac{v_{1}^{2}}{2*x_{1} } = \frac{(10.1m/s)^{2}}{2* 20.0m} = 2.6 m/s2 (8)[/tex]
Since v₀ = 0, applying the definition of acceleration, if we choose t₀=0, we can find t as follows:[tex]t_{1} =\frac{v_{1} }{a} =\frac{10.1m/s}{2.6m/s2} = 4.0 s (9)[/tex]
B)
Since we know the initial speed for this part, the acceleration, and the time, we can use the kinematic equation for displacement, as follows:[tex]x_{2} = v_{1} * t_{2} + \frac{1}{2} *a_{2}*t_{2}^{2} (10)[/tex]
Replacing the values of v₁ = 10.1 m/s, t₂= 2.0s and a₂=-1.5m/s2 in (10):[tex]x_{2} = 10.1m/s * 2.0s + \frac{1}{2} *(-1.5m/s2)*(2.0s)^{2} = 17.2 m (11)[/tex]
C)
From (6) and (8), applying the definition for acceleration, we can find the speed of the child whem she started up the second slope, as follows:[tex]v_{2} = v_{1} + a_{2} *t_{2} = 10.1m/s - 1.5m/s2*2.0s = 7.1 m/s (12)[/tex]
D)
Assuming no friction, all the kinetic energy when she started to go up the second slope, becomes gravitational potential energy when she reaches to the maximum height (her speed becomes zero at that point), so we can write the following equation:[tex]\frac{1}{2}*v_{2}^{2} = g*h_{2} (13)[/tex]
Replacing from (12) in (13), we can solve for h₂:[tex]h_{2} =\frac{v_{2} ^{2}}{2*g} = \frac{(7.1m/s) ^{2}}{2*9.8m/s2} = 2.57 m (14)[/tex]
Since we know that the slide makes an angle of 20º with the horizontal, we can find the distance traveled up the slope applying the definition of sine of an angle, as follows:[tex]x_{3} = \frac{h_{2} }{sin 20} = \frac{2.57m}{0.342} = 7.5 m (15)[/tex]
Which plate is the South American plate?
Answer:
The south American plate
Newtons third law is called law of action and reaction?
Answer:
His third law states that for every action (force) in nature there is an equal and opposite reaction. In other words, if object A exerts a force on object B, then object B also exerts an equal and opposite force on object A. ... In reaction, a thrusting force is produced in the opposite direction.
Explanation:
Answer:
These two forces are called action and reaction forces and are the subject of Newton's third law of motion Formally stated Newton's third law is For every action
Explanation:
A police officer is parked by the side of the road, when a speeding car travelling at 50 mi/hrpasses. The police car immediately pursues it, accelerating at a rate of 10 mi/hr per second.The road is fairly busy, so the officer will not go faster than a top speed of 70 mi/hr. How longwill it take before the officer catches up to the speeding car, and how far will it have travelled inorder to do so
Answer:
a) time taken to catch up with speeding car is 12.25 secs
b) the police car will travel 273.8 m to catch up with the speeding car
Explanation:
Given that;
speed of car [tex]V_{c}[/tex] = 50 mi/hr = 22.352 m/s
acceleration of police car = 10 mi/hr = 4.47 m/s²
[tex]V_{f}[/tex] = 70 mi/hr = 31.29 m/s
Now time taken to reach maximum speed is t₁
so
[tex]V_{f}[/tex] = [tex]V_{i}[/tex] + at₁
we substitute
31.29 = 0 + 4.47t₁
t₁ = 31.29 / 4.47
t₁ = 7 sec
now
d₁ = 0 + 1/2 × at₁²
d₁ = 0 + 1/2 × 0 + 4.47×(7)²
d₁ = 109.5 m
so distance travelled by the speeding car in time t₁ will be
[tex]d_{c}[/tex] = [tex]V_{c}[/tex] × t₁
we substitute
[tex]d_{c}[/tex] = 22.352 × 7
[tex]d_{c}[/tex] = 156.46 m
now distance between polive car and speeding car
Δd = [tex]d_{c}[/tex] - d₁
Δd = 156.46 - 109.5
Δd = 46.96 m
time taken to cover Δd will be
t₂ = Δd / ( [tex]V_{f}[/tex] - [tex]V_{c}[/tex] )
t₂ = 46.96 / ( 31.29 - 22.352 )
t₂ = 46.96 / 8.938
t₂ = 5.25 sec
distance travelled by the police in time t₂ will be
d₂ = [tex]V_{f}[/tex] × t₂
d₂ = 31.29 × 5.25
d₂ = 164.3 m
a) How long will it take before the officer catches up to the speeding car;
time taken to catch up with speeding car;
t = t₁ + t₂
t = 7 + 5.25
t = 12.25 secs
Therefore, time taken to catch up with speeding car is 12.25 secs
b) how far will it have travelled in order to do so;
distance = d₁ + d₂
distance = 109.5 + 164.3
distance = 273.8 m
Therefore, the police car will travel 273.8 m to catch up with the speeding car
One reason why it’s often easy to miss an action-reaction pair is because of the ________ of one of the objects.
Answer:
an action-reaction pair is because one of the objects is often much more massive and appears to remain motionless when a force acts on it. It has so much inertia, or tendency to remain at rest, that it hardly
Through what potential difference should electrons be accelerated so that their speed is 1.0 % of the speed of light when they hit the target
Answer:
Explanation:
Considering non - relativistic approach : ----
Speed of electron = 1 % of speed of light
= .01 x 3 x 10⁸ m /s
= 3 x 10⁶ m /s
Kinetic energy of electron = 1/2 m v²
= .5 x 9.1 x 10⁻³¹ x ( 3 x 10⁶ )²
= 40.95 x 10⁻¹⁹ J
Kinetic energy in electron comes from lose of electrical energy equal to
Ve where V is potential difference under which electron is accelerated and e is electronic charge .
V x e = kinetic energy of electron
V x 1.6 x 10⁻¹⁹ = 40.95 x 10⁻¹⁹
V = 25.6 Volt .
Someone please help me, I’m so lost my brain hurts
-- It takes 100 calories of heat to make 10 grams of the stuff 20° warmer.
How much of the heat warms each gram ?
-- It takes 10 calories of heat to make each gram of the stuff 20° warmer.
How much of the heat warms that gram each degree ?
-- It takes 1/2 calorie of heat to make each gram of the stuff 1° warmer.
The specific heat of that stuff is
(1/2 calorie) per gram per °C.
That's choice-3 .
Explanation:
The answer is No. 3
0.5 cal/g°C
I’m not sure how to solve this
Answer:
Option 10. 169.118 J/KgºC
Explanation:
From the question given above, the following data were obtained:
Change in temperature (ΔT) = 20 °C
Heat (Q) absorbed = 1.61 KJ
Mass of metal bar = 476 g
Specific heat capacity (C) of metal bar =?
Next, we shall convert 1.61 KJ to joule (J). This can be obtained as follow:
1 kJ = 1000 J
Therefore,
1.61 KJ = 1.61 KJ × 1000 J / 1 kJ
1.61 KJ = 1610 J
Next, we shall convert 476 g to Kg. This can be obtained as follow:
1000 g = 1 Kg
Therefore,
476 g = 476 g × 1 Kg / 1000 g
476 g = 0.476 Kg
Finally, we shall determine the specific heat capacity of the metal bar. This can be obtained as follow:
Change in temperature (ΔT) = 20 °C
Heat (Q) absorbed = 1610 J
Mass of metal bar = 0.476 Kg
Specific heat capacity (C) of metal bar =?
Q = MCΔT
1610 = 0.476 × C × 20
1610 = 9.52 × C
Divide both side by 9.52
C = 1610 / 9.52
C = 169.118 J/KgºC
Thus, the specific heat capacity of the metal bar is 169.118 J/KgºC
Points A, B, and C lie along a line from left to right, respectively. Point B is at a lower electric potential than point A. Point C is at a lower electric potential than point B. What would best describes the subsequent motion, if any, of a positively-charged particle released from rest at point B?
Answer:
Please see below as the answer is self-explanatory.
Explanation:
If the potential at B is lower than A, and the potential at C is lower than B, this means that there is an electric field, directed from A to C.If a positively-charged particle is released at rest at point B, it will be accelerated by the electric field (which is a force per unit charge, so it produces an acceleration) in the same direction than the field (because it is a positive charge) towards point C.Determine the magnitude of the gravitational force (in nano-Newton's, i.e. 10^-9N) between a 61.6 kg girl and a 71.2 kg boy standing 95 m apart from one another.
Answer:
3.24×10¯² nN
Explanation:
From the question given above, the following data were obtained:
Mass of girl (M₁) = 61.6 kg
Mass of boy (M₂) = 71.2 kg
Distance apart (r) = 95 m
Gravitational constant (G) = 6.67×10¯¹¹ Nm²/Kg²
Force (F) =?
The force of attraction between the girl and the boy can be obtained as follow:
F = GM₁M₂ /r²
F = 6.67×10¯¹¹ × 61.6 × 71.2 / 95²
F = 6.67×10¯¹¹ × 61.6 × 71.2 / 9025
F = 3.24×10¯¹¹ N
Finally, we shall convert 3.24×10¯¹¹ N to nN. This can be obtained as follow:
1 N = 10⁹ nN
Therefore,
3.24×10¯¹¹ N = 3.24×10¯¹¹ N × 10⁹ nN / 1 N
3.24×10¯¹¹ N = 3.24×10¯² nN
Thus, the force attraction between the girl and the boy is 3.24×10¯² nN
in a football game, the kicker kicks a football a horizontal distance of 43 yards if the ball lands 3.9 seconds later, what is the balls horizontal velocity
Answer:
10s
Explanation:
Horizontal velocity is the velocity of an object in an horizontal direction
The ball's horizontal velocity is approximately 33.078 ft./s
Reason:
The known parameter are;
The horizontal distance the footballer kicks the ball, d = 43 yards
The time after which the ball lands, Δt = 3.9 seconds
Required:
To find the velocity of the ball
Solution:
[tex]Velocity = \dfrac{Distance}{Time} = \dfrac{d}{\Delta t}[/tex]
Therefore;
[tex]Horizontal \ velocity \ of \ the \ ball, \ v_x= \dfrac{43 \ yard}{3.9 \ seconds} \approx 11.026 \ yd/s[/tex]
The ball's horizontal velocity, vₓ ≈ 11.026 yd/s
1 yard = 3 feet
[tex]11.026 \ yard = 11.026 \ yard \times \dfrac{3 \ feet}{yard} = 22.078 \ feet[/tex]
The ball's horizontal velocity, vₓ ≈ 33.078 ft./s
Learn more about horizontal velocity here:
https://brainly.com/question/14898646
Which object exerts the action force?
Which object exerts the reaction force?
In what direction does the action force push?
In what direction does the reaction force push?
For answering this question,let us assume that a person is pushing against the walls,so now:
Which object exerts the action force?
PersonWhich object exerts the reaction force?
WallIn what direction does the action force push?
BackwardIn what direction does the reaction force push?
ForwardThe answer varies from different scenarios.
Answer:
diver, diving board, down, and up.
Explanation:
A 72-kg man stands on a spring scale in an elevator. Starting from rest, the elevator ascends, attaining its maximum speed of 1.2 m/s in 0.80 s. The elevator travels with this constant speed for 5.0 s, undergoes a uniform negative acceleration for 1.5 s, and then comes to rest. What does the spring scale register During the first 0.80s of the elevator’s ascent?
Answer:
Explanation:
During the first .8 s , the elevator is under acceleration . It starts from initial velocity u = 0 , final velocity v = 1.2 m /s , time = .8 s
v = u + at
1.2 = 0 + .8 a
a = 1.2 / .8
= 1.5 m /s²
During the acceleration in upward direction , let reaction force of ground on man be R .
Net force on man = R - mg
Applying Newton's 2 nd law
R - mg = ma
R = m ( g + a )
= 72 ( 9.8 + 1.5 )
= 813.6 N .
This reaction force will be measured by spring scale , so reading of spring scale will be 813.6 N .
A river flows with a uniform velocity vr. A person in a motorboat travels 1.22 km upstream, at which time she passes a log floating by. Always with the same engine throttle setting, the boater continues to travel upstream for another 1.45 km, which takes her 69.1 min. She then turns the boat around and returns downstream to her starting point, which she reaches at the same time as the same log does. How much time does the boater spend traveling back downstream
Answer:
t ’= [tex]\frac{1450}{0.6499 + 2 v_r}[/tex], v_r = 1 m/s t ’= 547.19 s
Explanation:
This is a relative velocity exercise in a dimesion, since the river and the boat are going in the same direction.
By the time the boat goes up the river
v_b - v_r = d / t
By the time the boat goes down the river
v_b + v_r = d '/ t'
let's subtract the equations
2 v_r = d ’/ t’ - d / t
d ’/ t’ = 2v_r + d / t
[tex]t' = \frac{d'}{ \frac{d}{t}+ 2 v_r }[/tex]
In the exercise they tell us
d = 1.22 +1.45 = 2.67 km= 2.67 10³ m
d ’= 1.45 km= 1.45 1.³ m
at time t = 69.1 min (60 s / 1min) = 4146 s
the speed of river is v_r
t ’= [tex]\frac{1.45 \ 10^3}{ \frac{ 2670}{4146} \ + 2 \ v_r}[/tex]
t ’= [tex]\frac{1450}{0.6499 + 2 v_r}[/tex]
In order to complete the calculation, we must assume a river speed
v_r = 1 m / s
let's calculate
t ’= [tex]\frac{ 1450}{ 0.6499 + 2 \ 1}[/tex]
t ’= 547.19 s
Pam rubs a balloon on her head to generate a static charge. She holds the balloon up against a wall. Which of the following describes the electric charges and forces at work if the balloon sticks to the wall?
Electrons move from Pam’s hair to the balloon and attract electrons in the wall.
Electrons move from Pam’s hair to the balloon and attract protons in the wall.
Protons move from Pam’s hair to the balloon and attract protons in the wall.
Protons in the balloon form chemical bonds with protons in the wall.
Answer:
c
Explanation:
If the balloon sticks to the wall then electrons move from Pam’s hair to the balloon and attract protons in the wall.
One of the ways of producing static electricity is by the use of friction. Friction occurs when two surfaces are rubbed together. This leads to the loss of electrons from one of the surface which attracts the protons on another surface.
If the balloon sticks to the wall then electrons move from Pam’s hair to the balloon and attract protons in the wall.
Learn more about static electricity:https://brainly.com/question/821085
Please give a step by step explanation: 30 points up for grabs.
Answer:
Honestly, I don't know ¯\_(ツ)_/¯
Explanation:
The surface area of a postage
stamp is 0.00600 m^2, and the air
exerts 1.00 atm of pressure on it.
How much force does it exert on
the stamp?
(Hint: The standard unit for
pressure is Pa.)
(Unit = N)
Answer:
Force = 607.95 Newton
Explanation:
Given the following data;
Area = 0.00600 m^2
Pressure = 1 atm to Pascal = 101325 Pa
To find the force;
Pressure = Force/area
Force = pressure * area
Substituting into the equation, we have;
Force = 101325 * 0.00600
Force = 607.95 Newton.
Therefore, the amount of force exerted by the air on the stamp is 607.95 Newton.
A car is sitting still. It accelerates to a constant speed then it decelerates again to zero speed. While the car is accelerating how do the directions of the angular acceleration and angular velocity of one of the wheels compare
Answer:
in the acceleration process the quantity α and w must increase
the deceleration process the alpha quantity must constant a direction opposite to the angular velocity
Explanation:
Acceleration and angular velocity are related to linear
v = w xr
a = αx r
The bold letters indicate vectors and the cross is a vector product, therefore if
we can see that the relationship between linear and angular variables is direct
therefore in the acceleration process the quantity α and w must increase as well as their linear counterparts
in the deceleration process the alpha quantity must constant as the linear acceleration and must have a direction opposite to the angular velocity
A student weighing 5.4 × 102 newtons takes 15 seconds to run up a hill. The top of the hill is 10 meters vertically above her starting point. What power does the student develop during her run?
Answer:
P = 360 Watts
Explanation:
Given that,
The weight of a student, [tex]F=5.4\times 10^2\ N[/tex]
It takes 15 seconds to run up a hill.
The top of the hill is 10 meters vertically above her starting point.
We need to find the power develop during her run. We know that te power developed is given by :
[tex]P=\dfrac{W}{t}\\\\P=\dfrac{mgh}{t}\\\\P=\dfrac{5.4\times 10^2\times 10}{15}\\\\P=360\ W[/tex]
So, the power develop during her run is 360 W.
define stress engineering science
Answer:
Stress, in physical sciences and engineering, force per unit area within materials that arises from externally applied forces, uneven heating, or permanent deformation and that permits an accurate description and prediction of elastic, plastic, and fluid behaviour.
I hope it's helpful!
An ideal monatomic gas initially has a temperature of 300 K and a pressure of 5.79 atm. It is to expand from volume 420 cm3 to volume 1450 cm3. If the expansion is isothermal, what are (a) the final pressure and (b) the work done by the gas
Answer:
a) The final pressure is 1.68 atm.
b) The work done by the gas is 305.3 J.
Explanation:
a) The final pressure of an isothermal expansion is given by:
[tex] T = \frac{PV}{nR} [/tex]
[tex] T_{i} = T_{f} [/tex]
[tex] \frac{P_{i}V_{i}}{nR} = \frac{P_{f}V_{f}}{nR} [/tex]
Where:
[tex]P_{i}[/tex]: is the initial pressure = 5.79 atm
[tex]P_{f}[/tex]: is the final pressure =?
[tex]V_{i}[/tex]: is the initial volume = 420 cm³
[tex]V_{f}[/tex]: is the final volume = 1450 cm³
n: is the number of moles of the gas
R: is the gas constant
[tex] P_{f} = \frac{P_{i}V_{i}}{V_{f}} = \frac{5.79 atm*420 cm^{3}}{1450 cm^{3}} = 1.68 atm [/tex]
Hence, the final pressure is 1.68 atm.
b) The work done by the isothermal expansion is:
[tex] W = P_{i}V_{i}ln(\frac{V_{f}}{V_{i}}) = 5.79 atm*\frac{101325 Pa}{1 atm}*420 cm^{3}*\frac{1 m^{3}}{(100 cm)^{3}}ln(\frac{1450 cm^{3}}{420 cm^{3}}) = 305.3 J [/tex]
Therefore, the work done by the gas is 305.3 J.
I hope it helps you!
Fred's lightbulb is 45% efficient, and Fran's is 75% efficient. If they both use the same amount of electric energy, which produces more light energy?
Answer:
Frank's 75% efficient light bulb will shine brighter.
Explanation:
The brightness of a bulb is gotten from the power equation;
P = I²R
The more the power rating in watts, the more the brightness.
Now, if they both use the same amount of energy but yet have different efficiency, it means we will just multiply the efficiency by the power.
Thus, 75% efficiency will yield more power than a 45% efficient one.
Therefore, Frank's light bulb will shine brighter.
a car traveling at 30m/s slows down to a stop 10s. what is the acceleration?
Answer:
20 m/s. have a great day
Answer:
since v decreased by 20m/s in 5 sec, a = -4 m/s^2
assuming the 3 seconds started at t=0,
s = 30t - 2t^2
s(3) = 30(3) - 2(9) = 72m
What is the difference between elastic PE and gravitational PE?
Can someone help me answer please
Answer:
4=Conduction by convection by radiation.
Explanation:
Hope it will help you! It may be short but I don't know how to write it in blank aafai milayera lekha Hai blanks ma
First you lift an object from the floor onto a shelf. Then you move the object back to the floor. do you perform the same amount of work each time? Explain.
A simple pendulum of length 5.5 m makes 10.0 complete swings in 25 s what is the acceleration due to gravity at the location of the pendulum ?
Answer:
The acceleration due to gravity at the location of the pendulum is 34.74 m/s².
Explanation:
Given that,
The length of a simple pendulum, l = 5.5 m
It makes 10.0 complete swings in 25 s.
Frequency of pendulum,
[tex]f=\dfrac{10}{25}\\\\f=0.4\ Hz[/tex]
The time period of a simple pendulum is given by :
[tex]T=2\pi \sqrt{\dfrac{l}{g}}[/tex]
Frequency,
[tex]f=\dfrac{1}{T}\\\\f=\dfrac{1}{2\pi \sqrt{\dfrac{l}{g}} }\\\\f=\dfrac{1}{2\pi}\sqrt{\dfrac{g}{l}}[/tex]
g is the acceleration due to gravity at the location where the pendulum is placed. So,
[tex]f^2=\dfrac{g}{4\pi^2l}\\\\g=f^2\times 4\pi^2l\\\\g=0.4^2\times 4\pi^2\times 5.5\\\\g=34.74\ m/s^2[/tex]
So, the acceleration due to gravity at the location of the pendulum is 34.74 m/s².
What is the mass of an object if it is moving at a speed of 10 m/s and has 400 J of kinetic energy?
Answers:
8 kg
Explanation:
Kinetic Energy = (mass × velocity × velocity) ÷ 2
We know that Kinetic Energy = 400 J and velocity = 10 m/s.
KE = (m × v × v) ÷ 2
400 J = (m × 10 m/s × 10 m/s) ÷ 2
400 J = m × 50 m^2/s^2
To find the mass you will divide 400 J and 50 m^2/s^2.
m = 8 kg
You can also check it if it gives you 400 J.
KE = (m × v × v) ÷ 2
KE = (8 kg × 10 m/s × 10 m/s) ÷ 2
KE = 400 J
So this means that the mass is 8 kg. I know that it is a bit confusing, but when you do J (joules) ÷ m^2/s^2 = kg (kilograms). Hope this helps, thank you !!
Which of the following best describes what were wrong with the scientists study
calculate the peak voltage of a mains supply of 240Vrms.
Predictions about the future based on the position of planets is an example of
- physics
- biology
- earth science
- pseudoscience
Answer:
astronomi
Explanation:
sciemce ya ya