Dynamics and Space Mock Assessment 2.1
1 A snowboarder sets off from rest and accelerates uniformly at 4.1 m s -2 down a straight run.
(a) After 3.9 seconds the skier reaches a speed of 16 m s -1 and maintains this speed for a further
11 s.
(b) State what is meant by an acceleration of 4.1 m s -2
(c) Calculate the distance travelled by the skier during the first 3.9 s.
(d) Explain, in terms of the forces acting on the skier, why the skier
(e) continues to travel at 16 m s -1 after the first 3.9 s.
2 A golf ball is hit by a club and leaves the club with a momentum of 2·90 kgms -1 . The club is in contact with the ball for a time of 0·270 s.
(a) Calculate the average force exerted by the racquet on the ball.
(b) (b)The graph shows how the force, F , exerted on the ball by the club varies with time t .
F
0 i. t
(c) State what quantity is represented by the area under a force-time graph.
(d) The experiment is now repeated using a soft squash ball. This ball receives the same momentum as the golf ball. i. Copy the graph and draw an additional line to show how the force varies with time for the sponge ball. ii. You must label each line clearly.
3 A football is kicked and leaves the ground with an initial velocity of 13 m s -1 at an angle of 35 o to the horizontal as shown.
13m s -1
35 o
(a) State what happens to the magnitude of the vertical velocity of the football as it climbs to its maximum height.
(b) Assume that air resistance is negligible.
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(c) Calculate the horizontal component of the initial velocity of the ball.
(d) Calculate the vertical component of the initial velocity of the ball.
(e) Calculate the maximum height reached by the ball.
(f) The total time of flight is 1 ·62 s.
(g) Calculate the horizontal distance travelled by the ball in this time.
(h) The ball is kicked again with the same initial speed but at a smaller angle to the horizontal. Predict how this affects the maximum height reached by the football.
4 Explain what is meant by time dilation.
(a) A spacecraft leaves Earth and travels at a constant speed of 0·4 c to its destination.
(b) An astronaut on board the spacecraft measures the time to reach its destination to be exactly 2·5 years.
(c) Calculate the time taken for the journey as measured by an observer on Earth.
5 An ambulance is approaching a stationary pedestrian.
(a) The siren on the ambulance emits sound with a frequency of
840 Hz. The speed of sound in air is 3∙40 × 10 2 m s -1 .
(b) The ambulance is travelling at a constant speed of 22 m s -1 . Calculate the frequency heard by the pedestrian as the ambulance approaches.
(c) Explain in terms of wavefronts why the sound heard by the pedestrian is different from the frequency emitted by the siren.
(d) Light from a distant galaxy exhibits redshift .
What is meant by the term redshift ?
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6 State one piece of evidence that supports the Big Bang theory.
All hot objects emit electromagnetic radiation over a range of wavelengths.
The peak wavelength, λ p
, of the emitted radiation is inversely proportional to the kelvin temperature, T , of the hot object as shown by the following graph.
(a) The peak wavelength of a distant star is 714 nm so 1/ λ p
= 1 ·4 × 10 6 (m -1 )
Use the graph to determine the temperature of the star
(b) Show by calculation which of the following options describes the relationship between the temperature, T , in K, and peak wavelength, λ p
, in m
(c) T = 3 × 10 -3 λ p
(d) T = 3 × 10 -3
λ p
(e) T = 333
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λ p
(f) T = 333 λ p
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