ST VENERA BOYS’ SECONDARY SCHOOL HALF …stc.veneraboys.skola.edu.mt/Exam Papers/Form 4/F4 Physics...

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ST VENERA BOYS’ SECONDARY SCHOOL

HALF-YEARLY EXAMINATIONS 2014-15

Form 4 Physics (Track 3) Time: 1hr 30mins

Name: _____________________________ Class: ___________

Answer ALL questions in the spaces provided on the exam paper.

All working must be shown. The use of a calculator is allowed.

Where necessary take the acceleration due to gravity, g to be 10 m/s2.

Forces & Motion

W = m g F = m a

v = u + a t s = u t + ½ a t2

s = 2

v) (u t v2 = u2 + 2 a s

time Total

distance Total speed Average Momentum (p) = m v

Waves v = f λ T

1 f

Number 1 2 3 4 5 6 7 8 Total

Maximum mark 8 8 8 8 8 15 15 15 85

Actual mark

Total Theory Total Practical Final Mark

Actual Mark

Maximum Mark 85 15 100

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SECTION A This section carries 40 marks

1. The distance-time graph shown below shows the motion of a man during a short

ride with his bike:

a. Describe the motion of the boy

i. Between 0 to 30 s (1)

_________________________________________________________________________________

ii. Between 30 to 50 s (1)

_________________________________________________________________________________

b. i. What is the distance travelled after 15 s? _________________________________ (1)

ii. At what time is the distance travelled 100 m? ______________________________ (1)

c. From the graph, or otherwise, calculate the speed at which the boy cycles,

between 50 to 80 s. (2)

_________________________________________________________________________________

_________________________________________________________________________________

d. On the graph, mark with letters AB the part of the graph where the boy is travelling

fastest. Explain why you chose this part. (2)

_________________________________________________________________________________

_________________________________________________________________________________

distance-time graph

dis

tan

ce (

m)

(m)(

m)

time (s)

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2. In a drag race a car starts from rest on a straight track and accelerates uniformly to

reach a velocity of 120 m/s in 5 s.

a. What is the initial velocity, u, of the car? __________ (1)

b. What is the final velocity, v, of the car? __________ (1)

c. Calculate the acceleration of the car. (2)

_________________________________________________________________________________

_________________________________________________________________________________

d. Find the distance moved during these 5 s. (2)

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

e. If the total mass of the car and driver is 1400 kg, what is the resultant force on them?

_________________________________________________________________________________

_________________________________________________________________________________

f. Use your answer from part e) to calculate the driving force produced by the engine

if the total force opposing the motion of the car is 4000 N. (1)

_________________________________________________________________________________

_________________________________________________________________________________

3. Steve is driving at 45 m/s. The car in front of him stopped suddenly and he had to

react quickly and press the brake pedal.

a. Define the following term and mention one factor that affects it. (2)

Definition Factor

(1)

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Braking

distance

b. Steve takes 0.8 s to reach and press the brake pedal. What is the distance travelled

during this time? (2)

_________________________________________________________________________________

_________________________________________________________________________________

c. After pressing the brake pedal it took him a distance of 50 m to bring the car to a

stop. Calculate:

i. The total stopping distance. (1)

_________________________________________________________________________________

ii. The total time taken to stop the car. (2)

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

d. Had Steve been using a mobile phone, how would this affect the thinking

distance? (1)

_________________________________________________________________________________

_________________________________________________________________________________

4. Jack jumps off from a helicopter wearing a parachute. He does not open the

parachute straight away. The graph below shows the velocity (y-axis) against time

(x-axis) during the first 10 seconds after Jack jumps.

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a. What is his velocity 2 seconds after he jumped? (1)

_________________________________________________________________________________

b. After how many seconds does he open his parachute? (2)

_________________________________________________________________________________

c. As the boy falls, forces are acting upon him.

i. What is the force that is pulling him down called? (1)

_________________________________________________________________________________

ii. What is the force acting upwards, opposing his motion, called? (1)

_________________________________________________________________________________

d. Which of the forces mentioned in (c) above is larger:

i. At 3 seconds? _______________________________________________________ (1)

ii. At 6 seconds? _______________________________________________________ (1)

e. Describe briefly the motion of skydiver after 8 seconds that he falls. (1)

_________________________________________________________________________________

5. Two fishermen in different boats are 40 m apart when a speedboat passes creating a

wave which causes the fishermen to bob up and down as shown in the diagram below.

40m

Wave direction

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a. Is the wave causing the fishermen to bob up and down a transverse or a

longitudinal wave? __________________________________________________________ (1) (1)

b. On the diagram above mark:

i. a crest with a letter C

ii. a trough with a letter T

iii. a wavelength with the symbol λ. (3) (3)

c. Calculate the wavelength of the water wave shown in the diagram. (1)

_________________________________________________________________________________

d. If the fishermen bob up and down once every 4 seconds until the speedboat wave

passes. What is the periodic time T of the wave? (1)

_________________________________________________________________________________

e. What is the frequency of the speedboat wave? (1)

_________________________________________________________________________________

f. Using your answers calculate the velocity of the wave. (1)

_________________________________________________________________________________

_________________________________________________________________________________

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SECTION B This section carries 45 marks

6. The following table shows the velocity of a car as it is moving along a level road.

velocity (m/s) 0 7.5 15 22.5 30 30 30 20 10 0

time (s) 0 5 10 15 20 30 40 50 60 70

a. Plot a graph of velocity in m/s on the y-axis against time in seconds on the x-axis on

the graph paper provided. (5) (5)

b. Label the graph with letters:

i. AB – to show where the car was accelerating. (1) (1)

ii. CD – to show where the car was decelerating. (1) (1)

c. Work out the total distance travelled by the car during the 70 s of its journey. (4)

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

d. i. Use your graph to find the acceleration of the car during the first

20.seconds. (2)

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

ii. The mass of the car is 920 kg. Work out the force in N required during this rate of

change of the car’s velocity. (2)

_________________________________________________________________________________

_________________________________________________________________________________

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7. During a physics lesson, the students were asked to investigate the behaviour of

water waves. The teacher provided the following apparatus so that they could

carry out their investigation.

a. On the diagram shown label the different components of the above experimental

set-up used by the students. (3)

b. Describe by how the students used the above set up to produce straight water

waves of different frequencies and then measured the corresponding wavelengths.

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

The students started off the experiment by investigating reflection and refraction of

water waves.

c. Complete each diagram to show how waves travel in each situation. (4)

(3)

Reflecting surface Glass block

i. ii.

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Finally, the students sent straight water waves towards a gap in a straight barrier as

shown in the diagram below:

d. Complete the diagram to show what happens to the waves that have passed

through the gap. (1)

e. What is this effect called? (1)

_________________________________________________________________________________

The students move the barrier to widen the gap as shown below.

f. Sketch on the diagram above how the waves on the other side of the gap would

look now. (1)

g. If the waves were made to have a higher frequency, in what way would the effect

differ? (1)

_________________________________________________________________________________

This same effect is experienced by radio waves as they travel over hills.

h. Which are diffracted more – long wavelength radio waves, or shorter wavelength TV

waves? (1)

_________________________________________________________________________________

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8. This question is about momentum.

a. A student wanted to investigate the principle of conservation of momentum using 2

wooden trolleys and a smooth, inclined runway which was compensated for

friction. He also used two light gates and two electronic timers to calculate the

velocities of the trolleys.

He measures the mass of each trolley using an electronic balance and then pushes

trolley A towards trolley B. Trolley B is initially at rest. He obtains the following results:

mass of trolley A = 0.350 kg,

mass of trolley B = 0.275 kg

velocity of trolley A (before collision) = 2.6 m/s

i. Calculate the momentum of trolley A, before it collides with trolley B. (2)

_________________________________________________________________________________

_________________________________________________________________________________

ii. What is the momentum of trolley B before the collision? (1)

_________________________________________________________________________________

iii. Hence calculate the total momentum of both trolleys before collision. (1)

_________________________________________________________________________________

iv. After the collision, the two trolleys stick together. What is their total momentum

after collision? (1)

_________________________________________________________________________________

v. Calculate the combined velocity of the trolleys after collision. (3)

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

trolley A trolley B

light gate

friction-

compensated

runway

card

electronic

timer

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b. A baseball player catches a ball of mass 0.15 kg when it is moving with a velocity of

19 m/s and he stops it.

i. Calculate the change in momentum of the baseball. (2)

_________________________________________________________________________________

_________________________________________________________________________________

ii. If the force exerted by the player to stop the ball is – 285 N, calculate the time

taken to stop the ball. (2)

_________________________________________________________________________________

_________________________________________________________________________________

_________________________________________________________________________________

iii. If the baseball was thrown with the same velocity but is stopped in a time of

0.014.s, how would the force exerted on the player change? (1)

_________________________________________________________________________________

c. Modern cars are built with a number of safety features designed to protect the

driver and passengers during a collision.

i. Give one example of a safety feature used in cars. (1)

_________________________________________________________________________________

ii. Explain how the safety feature you have indicated helps passengers in case of

an accident. (1)

_________________________________________________________________________________

_________________________________________________________________________________

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