Answer:
Short sight occurs when the eyeball is too long or the lens is too thick, or both. As a result, light rays from distant objects are focused in front of the retina (because the light rays are highly converged). The image formed on the retina is therefore out of focus.
Short sight can be corrected by wearing glasses with concave lenses. Light rays from distant objects are diverged by concave lenses before entering the eyes, so that light can be focused on the retina to form a sharp image.
A boy is twirling a model airplane on a string 4 feet long. if he twirls the plane at 0.25 revolutions per minute, how far does the plane travel in 4 minutes? round to the nearest tenth.
Answer:
25.13 ft
Explanation:
r = 4 feet
ω=0.25 revolution per minute
=1 revolution in 4 minutes
total number of revolution N = 1 (in 4 minutes )
v=rω
distance traveled = 2×N×π×r
=2×1×π×4
=8π
= 25.13ft in 4mins
Plzz answer this questions
will mark as brainlist
Answer:
1. 19.28 secs
2. 154.22 m
Explanation:
The following data were obtained from the question:
Initial velocity (u) = 16 m/s
Final velocity (v) = 0
Force (F) = 1000 N
Mass (m) = 1200 Kg
Time (t) =..?
Distance (s) =...?
Next, we shall determine the acceleration of the car. This can be obtained as follow:
Force (F) = 1000 N
Mass (m) = 1200 Kg
Acceleration (a) =.?
Force (F) = mass (m) x acceleration (a)
F = ma
1000 = 1200 x a
Divide both side by 1200
a = 1000/1200
a = 0.83 m/s²
Since the car is coming to rest, it means it is decelerating. Therefore, the acceleration is – 0.83 m/s²
1. Determination of time taken for the car to halt i.e stop. This can be obtained as follow:
Initial velocity (u) = 16 m/s
Final velocity (v) = 0
acceleration (a) = – 0.83 m/s²
Time (t) =.?
v = u + at
0 = 16 + (–0.83 x t)
0 = 16 – 0.83t
Rearrange
0.83t = 16
Divide both side by 0.83
t = 16/0.83
t = 19.28 secs.
Therefore, the time taken for the car to halt is 19.28 secs.
2. Determination of the distance travelled by the car before coming to rest. This can be obtained as follow:
Initial velocity (u) = 16 m/s
Final velocity (v) = 0
acceleration (a) = – 0.83 m/s²
Distance (s) =..?
v² = u² + 2as
0 = 16² + (2 x –0.83 x s)
0 = 256 – 1.66s
Rearrange
1.66s = 256
Divide both side by 1.66
s = 256/1.66
s = 154.22 m
Therefore, the distance travelled by the car before coming to rest is 154.22 m.
How is mercury barometer constructed ?
Answer:
A mercury barometer is a device use to measure stomspheric pressure and is constructed as following:
A mercury barometer requires a tube which has one close end, and one open end.Tube is placed upside down in a beaker in such a way so that one end open in the beaker and the other remain outside of the beaker. The barometric liquid (mercury) is then filled in the tube by pouring mercury liquid in the beaker.The position of tube creates vacuum between the closed end of the tube and liquid surface and the Mercury has high density that is why used as the liquid to measure pressure.
A gas occupies a volume of 1.0 m3 in a cylinder at a pressure of 120kPa. A piston compresses the gas until the volume is 0.25m3, the temperature remaining constant. What is the new pressure of the gas?
Answer:
Approximately [tex]480\; \rm kPa[/tex], assuming that this gas is an ideal gas.
Explanation:
Let [tex]V(\text{Initial})[/tex] and [tex]P(\text{Initial})[/tex] denote the volume and pressure of this gas before the compression. Let [tex]V(\text{Final})[/tex] and [tex]P(\text{Final})[/tex] denote the volume and pressure of this gas after the compression.By Boyle's Law, the pressure of a sealed ideal gas at constant temperature will be inversely proportional to its volume. Assume that this gas is ideal. By this ideal gas law:
[tex]\displaystyle \frac{P(\text{Final})}{P(\text{Initial})} = \frac{V(\text{Initial})}{V(\text{Final})}[/tex].
Note that in Boyle's Law, [tex]P[/tex] is inversely proportional to [tex]V[/tex]. Therefore, on the two sides of this equation, "final" and "initial" are on different sides of the fraction bar.
For this particular question:
[tex]V(\text{initial}) = 1.0\; \rm m^3[/tex].[tex]P(\text{Initial}) = 120\; \rm kPa[/tex].[tex]V(\text{final}) = 0.25\; \rm m^3[/tex].The pressure after compression, [tex]P(\text{Final})[/tex], needs to be found.Rearrange the equation to obtain:
[tex]\displaystyle P(\text{Final}) = \frac{V(\text{Initial})}{V(\text{Final})} \cdot P(\text{Initial})[/tex].
Before doing any calculation, think whether the pressure of this gas will go up or down. Since the gas is compressed, collisions between its particles and the container will become more frequent. Hence, the pressure of this gas should increase.
[tex]\begin{aligned}P(\text{Final}) &= \frac{V(\text{Initial})}{V(\text{Final})} \cdot P(\text{Initial})\\ &= \frac{1.0\; \rm m^{3}}{0.25\; \rm m^{3}} \times 120\; \rm kPa = 480\; \rm kPa\end{aligned}[/tex].
a body starts from rest and gains the velocity of 5 metre per second into second is it of uniform velocity explain
Answer:
It is not a uniform velocity, because his velocity increases for 5 m every second (acceleration = 5m/s2), meaning his velocity always changes.
When he starts at rest, his velocity is 0 m/s. But in 1 second later, his velocity is already 5m/s. At 2 seconds, his velocity will be 10 m/s.
DOUBLE POINTS!
A tuning fork of 500 Hz is struck in a room with a speed of sound of 340 m/s. What is the distance between a point of rarefaction and the next compression point, in the resulting sound?
[tex]\mathfrak{\huge{\pink{\underline{\underline{AnSwEr:-}}}}}[/tex]
Actually Welcome to the Concept of the Waves and it's motion.
So we here apply the formula as,
Velocity = frequency*wavelength
so here we get as,
340 = 500 * Lambda
Lambda = 340/500
so we get the distance as,
L = 0.68 m
Answer:
λ = 0.68 m
Explanation:
Distance between a point of rarefaction and the next compression point is actually the wavelength (λ)
So, we'll find wavelength here:
Given:
Frequency = f = 500 Hz
Speed = v = 340 m/s
Required:
Wavelength = λ = ?
Formula:
v = f λ
Solution:
λ = v/f
λ = 340/500
λ = 0.68 m
Determine the amount of time for polonium-210 to decay to one fourth its original quantity. The half-life of polonium-210 is 138 days. Explain.
Answer:
276 days
Explanation:
1/4 th of the original means 2 half lives
1 half life = 138 days
So,
2 half lives = 276 days
Q2. Zara travelled in a train moving at an average speed of 120km/h and covered a distance of 40km towards East. Calculate the time taken by the train to cover this distance.
Answer: 20 minutes
Explanation:
Given the following :
Average speed of train = 120km/hr
Distance = 40km.
The time take by the train moving at an average speed of 120km/hr to cover a distance of 40km due is ;
Recall:
Speed = distance / time
Therefore,
Time taken = distance covered / speed
Time taken = 40km / 120km/hr
Time taken = 1/ 3 hr
Therefore, 1/3 rd of an hour equals
1/3 × 60 = 20 minutes.
Time taken) 20 minutes
Time taken by tain to cover distance is 20 minutes as:
Distance= 40 km
Speed= 120 km/h
Time= distance/speed
= 40/120
= 1/3 hour
= 20 min
or =0.33 hrs
To know more about' Time and Speed 'visit:
https://brainly.com/question/28735144
Electrons that are free to move in metals
Answer:
Brainliest please
Explanation:
I will start by saying that Metals by their very nature are conductors of electricity. Now metals exhibit “metallic bonding” which holds its structure together. Unlike other materials which exhibit covalent bonding, it's atoms are not bonded by “electron sharing”. Rather they are bonded by the availability of valence electrons. Now within a metals atomic structure, the metal atoms lose the electrons in thier outermost shell (valence electrons), thus becoming positively charged ions (cations )
A man can walk three blocks east and four blocks north in 20 min. He can drive 12 times that distance in the same amount of time. How far can the man
drive in 20 min? Assume that each block is 0.3 kilometers.
Answer: 25.2 km
Explanation:
3 blocks east and four blocks east = 7 blocks
1 block = 0.3 km --> 7 blocks = 2.1 km
12 times 2.1 km = 25.2 km
Before beginning an experiment, Mrs. Wilson warns her science class not to drop the bar magnets on the floor. What is the most likely reason for Mrs. Wilson’s warning?
Answer:
we should not drop a magnet on the floor because the magnets tend to lose magnetism gradually and become weak over a period of time if they are not stored properly.
Answer:
Well depending on the floor like say if it was a wooden floor the magnet might lose it magnetism, if concrete floor the magnetic brake and still lose it magnetism, if a metal floor the magnet would stick not sure if it wood lose it magnetism or not but the possibilities still there, basically what I'm saying is the magnet would lose its magnetism if it were to interact with the floor maybe temporary or maybe permanently.
for those with with a learning disability it's a
Explanation:
Q- A body is acted upon by two forces 30N due east and 40N due North. Calculate
resultant and its direction.
Answer:
the following image will make you understand
Explanation:
as a motorcycle takes a sharp turn the type of motion that occurs is called ——— motion
Answer:
circular motion
Explanation:
hope this helps you :)
Answer:
Centripetal motion
Explanation:
As a motorcycle takes a sharp turn the type of motion that occurs is called centripetal motion
24. Heat transfer by convection occurs when: A. Atoms give off energy in the form of radiation B. A large number of atoms move from one place to another C. Electrons collide with other electrons and with atoms. D. Electromagnetic waves travel though space to heat up an object.
Answer:
B. A large number of atoms move from one place to another
Explanation:
Convection is heat transfer by the movement of atoms of a substance from one region to another across a temperature gradient. Since atoms of solids are rigidly held in place, convection only occurs in liquids and gases since they flow.
Convection occurs when the temperature of one region of a fluid (liquid or gas) is higher than its other region. There is thus a mass movement of atoms from one region to the other due to a temperature difference. The atoms will continue to move to the region of lower temperature until the temperature of both regions are the same at an equilibrium temperature.
The count rate of a radioactive source decreases from 1600 counts per minute to 400 counts per minute in 12 hours. What is the half-life of the source?
Answer:
[tex]t_{1/2}=6 h[/tex]
Explanation:
Let's use the decay equation.
[tex]A=A_{0}e^{-\lambda t}[/tex]
Where:
A is the activity at t timeA₀ is the initial activityλ is the decay constantWe know that [tex]\lambda=\frac{ln(2)}{t_{1/2}}[/tex]
So we have:
[tex]\lambda=\frac{ln(A/A_{0})}{t}[/tex]
[tex]\frac{ln(2)}{t_{1/2}}=\frac{ln(A/A_{0})}{t}[/tex]
[tex]t_{1/2}=\frac{t*ln(2)}{ln(A/A_{0})}[/tex]
[tex]t_{1/2}=6 h[/tex]
Therefore, the half-life of the source is 6 hours.
I hope it helps you!
Un resorte se alarga 5 cm bajo la acción de una fuerza de 39,2 N. ¿Cuál es la constante del resorte? Si ahora la fuerza es 68,6 N. ¿Cuál es el nuevo alargamiento?
Answer:
[tex]k=784 N/m[/tex]
[tex]\Delta x=8,8 cm[/tex]
Explanation:
Usando la ley de Hook tenemos:
[tex]F=k\Delta x[/tex]
Solving it for k we have:
[tex]k=\frac{F}{\Delta x}[/tex]
[tex]k=\frac{39,2}{0,05}[/tex]
[tex]k=784 N/m[/tex]
Usando la misma ecuación y sabiendo k tenemos:
[tex]\Delta x=\frac{F}{k}[/tex]
[tex]\Delta x=\frac{68,6}{784}[/tex]
[tex]\Delta x=8,8 cm[/tex]
Espero esto te ayude!
A man weighing 80kg is standing on a trolley weighing
320kg. The trolley resting on smooth horizontal rails. If
the man starts walking on the trolley along the rails with
a speed of 1ms", then his displacement relative to the
ground after 4 second is
1) 4.8 m 2) 4 m 3) 3.2 m 4) 2.8 m
Answer:
Net displacement = 3.2 m
Explanation:
Given:
Mass of man = 80 kg
Mass of trolley = 320 kg
Speed = 1 m/s
Time = 4 sec
Computation:
Displacement by man = 1 m/s × 4 sec
Displacement by man = 4 m
Net ext force (trolley) = com at rest
So,
320 × X = 80(4 - X)
32X = 32 - 8X
40X = 32
X = 0.8 m
Net displacement = 4 m - 0.8 m
Net displacement = 3.2 m
Answer:
3) 3.2 m
Explanation:
The computation of the displacement relative to the ground after 4 seconds is shown below:
Let us assume the following
Starting x coordinate is at the origin
As it does not involve any external force so x coordinated would remain unchanged
Now the separation between the man and the trolley is
[tex]= 4 \times 1[/tex]
= 4 m
And, we assume the displacement of man be x
So, for trolley it would be (4 -x)
Now we develop the equation which is
[tex]80 \times x = 320 \times (4 - x)[/tex]
x = 16 - 4x
Therefore x = 3.2 m
Which term describes the amount of energy that is used in a circuit each
second?
O A. Voltage
O B. Power
O c. Current
O D. Resistance
Answer:
The correct answer is power
Suppose that a driver applies a force of 140 N to the master cylinder, which has a diameter equal to 14 the diameter of the brake cylinder. What is the force applied by the brake cylinder on the brake shoe?
Answer:
force on brake shoes is 10 N
Explanation:
for the master cylinder;
force applied = 140 N
diameter = 14d
for brake cylinder;
force applied on the brake shoe by the brake cylinder f = ?
diameter = d
The pressure will be transmitted undiminished from the master cylinder to the brake cylinder according to pascals pressure law.
pressure = force/area
but cross sectional area is proportional to diameter of the cylinder
therefore
[tex]\frac{140}{14d } = \frac{f}{d }[/tex]
the diameters will cancel out, and we're left with
force on brake shoes = 10 N
Three 15.0-W resistors are connected in parallel across a 30.0-V battery. Please show all work.
a) Find the current through each branch of the circuit.
b) Find the equivalent resistance of the circuit.
c) Find the current through the battery.
Answer:
Part A)
Since all of the resistors have equal resistance, hence for finding even only 1 branch It will be fine because current will be the same for all branches.
=> [tex]I = \frac{V}{R_{1} }[/tex]
=> [tex]I = \frac{30}{15}[/tex]
=> I = 2 A
Part B)
Equivalent resistance for parallel circuits is the sum of reciprocals of each resistor.
=> [tex]\frac{1}{R} = \frac{1}{R_{1}}+\frac{1}{R_{2}} +\frac{1}{R_{3}}[/tex]
=> [tex]\frac{1}{R} = \frac{1}{15}+ \frac{1}{15}+\frac{1}{15}[/tex]
=> [tex]\frac{1}{R} = \frac{3}{15}[/tex]
=> R = 15/3
=> R = 5 ohms
Part C)
I = V/R
Where I is current, V is voltage and R is the equivalent resistance
=> I = 30/5
=> I = 6 A
One sprinter has a stride of 120cm, another 75cm. How many steps do they each take if they run a 100m race?
Explanation:
100 m / (1.20 m) = 83.3
100 m / (0.75 m) = 133.3
Rounded up, the first sprinter takes 84 steps, and the second sprinter takes 134 steps.
I NEED HELP PLEASE, THANKS! :)
Generate an explanation for the following formula: P = I²R . Explain.
Answer:
P = VI = (IR)I = I2R
Explanation:
What the equation means is that if you double the current you end up with 4 times the power loss. It's like the area of carpet you need for a room - if you make the room twice as long and twice as wide you need 4x as much carpet. The physical explanation is that the voltage difference along a wire depends on the current - more current flowing with a resistance means more voltage (pressure of electricity if you like) is built up.
This extra voltage means more power. So if you double the current your would double the power, but you also double the voltage which doubles the power again = 4x as much power. P = VI = (IR)I = I2R
I hope this helps you out, if I'm wrong, just tell me.
As I mentioned earlier, Ohm's law gives us the formula P = IV, where V is the voltage ( also known as the electrical potential difference ) and I is the current. It is confusing that P = I²R and P = IV are one in the same - so I want to go a bit deeper on that.
We have three formulas, P = IV, P = I²R, and P = V² / R. Each are considered the same. The two formulas P = I²R, and P = V² / R are derived from the statement that P = IV, under the condition V = IR. Substitute the value of V from this second condition V = IR into P = IV. You would get the following -
P = I( IR ),
P = I²R
That is how one can derive the formula P = I²R, and how P = IV and P = I²R are thought to be one in the same. If you would like, take a look at how to get the formula " P = V² / R, "
V = IR, P = IV
I = V / R, P = IV
P = ( V / R )V,
P = V² / R
Hope that helps!
the most common mineral group is broken into the subgroups of ferromagnesium and nonferromagnesium
Answer:
They're made of silicon and oxygen.
Explanation:
A runner starts from rest and speeds up with constant acceleration. If she
has gone a distance of 30 m at the point when she reaches a speed of 8 m/s,
what is her acceleration?
A. 7.5 m/s2
B. 3.8 m/s2
C. 9.1 m/s2
D. 1.1 m/s2
Answer:
a = 1.07 m/s^2
Explanation:
The computation of the acceleration is shown below:
As we know that
[tex]v_f^{2} - v_i^{2} = 2 ad[/tex]
where,
v_i = 0 m/s = initial speed
v f = 8 m/s = final speed
d = 30m = distance
Now placing these values to the above equation
[tex]8^{2} - 0 = 2 \times a \times 30[/tex]
64 = 60a
a = 1.07 m/s^2
We simply applied the above formula so that we could able to determine the acceleration
long nonconducting cylinder (radius = 12 cm) has a charge of uniform density (5.0 nC/m3) distributed throughout its volume. Determine the magnitude of the electric field 15 cm from the axis of the cylinder.
Answer:
the magnitude of the electric field = 27.1058 V/m
≈ 27 V/m
Explanation:
given
R(radius enclosed) = 12 cm = 0.12 m
ρ(charge density) = 5.0 nC/m³ = 5.0 × 10⁻⁹C/m³
r(radius from the axis) = 15 cm = 0.15 m
using Gauss law, which states that the electric flux through any closed surface is directly proportional to the total electric charge enclosed by this surface.
attached is the calculation of the question, using Gauss law of electrostatics
A car travels 500m in 50s, then 1,500m in 75s. Calculate its averages speed for the whole journey
Answer:
15m/s
Explanation:
500 ÷ 50 = 10m/s
1500 ÷ 75 = 20m/s
10 + 20 = 30
30 ÷ 2 = 15m/s
Answer: 16 miles per second
Explanation:
Find the total distance traveled and the total time.
[tex]\text{average rate}=\dfrac{1500+500}{75+50}=\dfrac{2000\ miles}{125\ second}=\large\boxed{16\ mps}[/tex]
How far away from the surface of earth does the acceleration due to gravity will be inclined by 36% of its value on the surface of earth? Radius of earth is 6400 km
Answer:
1,600 km
Explanation:
since the acceleration due to gravity reduces by 36%, it means that (1 - 36%) of acceleration still remains:
g' = 64g/100
using the acceleration formula:
g' = g x [R² / (R + height)²]
64g/100 = g x [R² / (R + height)²]
64/100 = R² / (R + height)²
√(64/100) = √[R² / (R + height)²]
8/10 = R / (R + height)
8 (R + height) = 10R
8R + 8height = 10R
8height = 2R
height = 2R / 8 = R / 4
R = 6,400 km
height = 6,400 km / 4 = 1,600 km
Answer:
The acceleration due to gravity will be inclined 1600 KM by 36% of its value on the surface of earthNewton’s third law of motion says that for every action there is a(n) and opposite reaction.
Answer:
for every action thete is an equal and opposite reaction
Answer:
Newton’s third law of motion says that for every action there is a(n)
equal and opposite reaction.
Explanation:
just got it right edg 1928
if spiderman runs and jumps horizontally from the top of a 200m high building, what does he need his velocity to be to land on a building 100m high, 10m away from him?
Answer:
v = 2.22 m/s
Explanation:
First we apply the second equation of motion to the vertical motion of the body:
s = Vi t + (1/2)gt²
where,
s = y = vertical distance covered = 200 m - 100 m = 100 m
Vi = V₀y = Vertical Component of Initial Velocity = 0 m/s (because spider man jumps horizontally, thus his velocity has no vertical component initially)
t = Time Taken to Land on 100 m high building = ?
g = 9.8 m/s²
Therefore,
100 m = (0 m/s)t + (0.5)(9.8 m/s²)t²
t² = (100 m)/(4.9 m/s²)
t = √(20.4 s²)
t = 4.5 s
Now, we analyze the horizontal motion. Neglecting air friction, the horizontal motion is uniform with uniform velocity. Therefore,
s = vt
where,
s = x = horizontal distance covered = 10 m
v = V₀ₓ = Horizontal Component of Initial Velocity = Initial Velocity = ?
Therefore,
10 m = v(4.5 s)
v = 10 m/4.5 s
v = 2.22 m/s
PLEASE I NEED HELP WITH THIS ASAP
A student finds a rock on the way to school. In the laboratory he determines that the volume of the rock by placing the rock in a graduated cylinder with 50 cm3 of water and watched the water rise to 72.7 cm3. The student determined the mass is 39.943 g through the use of a triple beam balance. What is the density of the rock?
With step by step explanation
Answer:
density=mass/volume
39.943/22.7=1.75
Explanation: