# Unit Test revision

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1.
(a) A car, initially at rest, accelerates uniformly at 4.8 ms-2 for 4 seconds and
then travels at constant speed for a further 8 seconds.
(b) State what is meant by an acceleration of 4.8 ms-2.
(c) Calculate the speed reached after 4 seconds.
(d) Calculate the distance travelled in the first 4 seconds.
(e) Explain, using Newton`s Laws why the car travels at constant speed.
2
(a) A stationary object is hit and moves off with a momentum of 4.5 kgms -1.
The time of contact is 0.17 s. Calculate the average force exerted on the
object
(b) Sketch a graph showing how the force on the object varies over the time
of contact
(c) The experiment is now repeated using an object made of softer material.
This object also moves off with a momentum of 4.5 kgms-1. Draw another
line on your sketch to show how the force varies for the new object.
3. A golf ball is hit and leaves the ground travelling at a speed of 25 ms-1 at an
angle of 300 to the horizontal. The ball travel in the air for 2.6 s.
(a) What happens to the vertical velocity of the ball as it rises to its maximum
height
(b) Calculate the initial horizontal and vertical components of the velocity
(c) Calculate the maximum height and the horizontal distance travelled by the
ball.
(d) What differences would be found if the ball was hit again and left with the
same initial speed but at a greater angle to the horizontal?
4.
(a) Explain what is meant by time dilation and length contraction.
(b) An object leaves a Solar System and travels at a constant speed of 0.5C. An observer
travelling in the object measures a journey time of 3 years. Calculate the journey
time measured by an observer in the Solar System.
5. A source of sound, of frequency 900Hz, is travelling at a constant speed of 32 ms-1 away
from a stationary observer.
(a) Calculate the frequency heard by the observer.
(b) Explain why the observer hears a frequency different from 900 Hz
(c) Explain what is meant by the term redshift.
6.
7.
State the evidence that supports the Big Bang Theory
Look at this graph
(a) What is the volume when the pressure is 150kPa?
(b) What is the numerical relationship between pressure, P and volume, V?