STCC
S.5 Physics
Mech Revision Quiz 1
2.12.15
Mr. Yau
1. During a high jump, when the jumper reaches the highest position,
(1)
the net force acting on him is zero.
(2)
his vertical speed is zero.
(3)
his acceleration is zero.
A.
(1) only
B.
(2) only
C.
(3) only
D.
(2) and (3) only
2. A ball on the ground is projected vertically upwards at time t = 0 with an initial velocity of 10 m s1. Which of the following
graphs best represents the subsequent motion of the ball? (Take upwards as positive. a = acceleration of the ball, v =
velocity of the ball)
A.
B.
a / m s2
9.81
9.81
0
C.
v / m s1
t/s
2
0
D.
a / m s2
t/s
2
v / m s1
9.81
9.81
0
0
2
2
t/s
t/s

9.81
1
3. A block is rest on an inclined rough surface. The block remains at rest when two forces of magnitudes 5N and 2 N act on it,
what is the resultant force acting on the block?
5N
2N
A.
0N
B.
2N
C.
3N
D.
7N
4. An object accelerates from rest uniformly. It travels a distance of 54 m in 3 seconds. Find the distance travelled by the object
in the 4th second.
A.
30 m
B.
42 m
C.
72 m
D.
96 m
1
5. A wooden block of mass 15 kg is pulled by a force of 80 N at an angle as shown in the figure. If the block moves horizontally
with an acceleration of 2 m s–2, find the friction between the block and the ground.
80 N
60
ground
A.
10 N
B.
70 N
C.
50 N
D.
110 N
6. A pair of forces FA and FB is indicated in each of the following cases. Which of them is/are the example(s) of action-andreaction pairs according to Newton’s third law?
(1)
FA
FA = normal reaction acting on the ball by the player
FB
FB = weight of the ball
(2)
FA = tension that holds the object
FA
FB = weight of the object
FB
(3)
FA
FA = force exerted on the plane by the ejected gas
FB = force exerted on the ejected gas by the plane
FB
A.
(2) only
B.
(1) and (2) only
C.
(3) only
D.
(2) and (3) only
2
7. A 3 kg block and a 2 kg block rest on a smooth horizontal surface as shown. When rope B is pulled by a 20 N force, the tensions
in the ropes A and B attached to the blocks become T1 and T2.
3 kg block
A
2 kg block
B
What are the magnitudes of T1 and T2?
T1
T2
A.
20 N
20 N
B.
20 N
12 N
C.
20 N
8N
D.
12 N
8N
8.
A uniform plank of mass m is supported by two trestles. Two men weighing 500 N and 750 N stand at the left and right ends
of the plank respectively. If the force exerting on the left trestle is zero, what is the value of m?
9.
A.
5 kg
B.
30 kg
C.
15 kg
D.
50 kg
Two identical blocks A and B travel down two different tracks as shown.
Assuming that friction is negligible. Which of the following statements are correct?
(1)
The potential energy lost by block A is the same as that of block B when they reach the end of the track.
(2)
The speed of block A is the same as that of block B when they reach the end of the track.
(3)
Block A and block B reach the end of the track at the same time.
A.
(1) and (2) only
B.
(2) and (3) only
C.
(1) and (3) only
D.
(1), (2) and (3)
3
10. Which of the following diagrams correctly shows the resultant force F of two forces F and F ?
1
2
A.
F1
F1
F
F2
C.
B.
F1
F
F2
D.
F1
F
F
F2
11.
12.
F2
A man in a lift starts to accelerate downwards. How does he feel?
A.
He feels as if he is in a stationary lift.
B.
He feels a loss in weight.
C.
He feels a gain in weight.
D.
He feels weightless.
A policeman chases a thief along a straight road. He starts from rest and accelerates at 1.5 m s –2 for 6 s. Find the distance that
he has run.
13.
14.
A.
13 m
C.
25 m
B.
21 m
D.
27 m
A man hits a volleyball with a force F. Which of the following is an action-and-reaction pair?
A.
The weight of the volleyball and force F.
B.
Force F and the friction acting on the volleyball.
C.
The weight of the volleyball and the normal reaction acting by air on the volleyball.
D.
Force F and the force acting by the volleyball on the man’s hand.
Which of the following phenomena can be explained by inertia?
A.
A passenger in a MTR train tends to move backwards when the train speeds up.
B.
A coin and a piece of paper fall with the same acceleration in a vacuum.
C.
A tank recoils when it fires.
D.
A man weighs less on the Moon than on the Earth.
4
15.
A ball-bearing is released at E of a smooth rail.
Which of the following graphs is/are correct?
(1)
kinetic energy
(2)
potential
(3)
16.
total energy
A. (1) and (2) only
C.
(2) and (3) only
B. (1) and (3) only
D.
(1), (2) and (3)
CN Tower in Canada is 533 m tall and it is the second tallest building in the World. If a stone of 200 g is thrown vertically
upwards at 5 m s1 at the top of the CN Tower, what is the kinetic energy of the stone when it drops to the ground? Neglect
air resistance.
A.
535 J
C.
1500 J
B.
1050 J
D.
2140 J
5
A bicycle of mass 15 kg decelerates from 5 m s–1 to rest in 5 s. What is the change in momentum of the cyclist whose mass is
17.
65 kg?
A.
–37.5 kg m s
B.
–75 kg m s
1
1
C.
–162.5 kg m s
D.
–325 kg m s
1
1
Trolley A of mass 1.5 kg moves at a constant velocity of 2 m s–1. It collides trolley B of mass 1 kg which is originally moving
18.
in the opposite direction at a constant velocity of 3 m s–1. After the collision, two trolleys stick together. Find the velocity of
the trolleys after the collision.
19.
1
A.
0ms
B.
2.4 m s
1
C.
2ms
D.
3ms
1
1
The figure below shows the motions of the two balls A and B before and after collision. Both balls move on a smooth ground.
Ball B is at rest before collision.
B
A
B
A
Which of the following statements about the collision must be correct?
20.
(1)
The total momentum of the balls is conserved.
(2)
The total KE of the balls is conserved.
(3)
The magnitude of the force of impact acting on B by A is equal to that on A by B.
A.
(1) only
C.
(1) and (3) only
B.
(3) only
D.
(2) and (3) only
A ball falls from a height of h to the ground and bounces back to the same height. Which of the following statements is/are
correct?
21.
(1)
The momentum of the ball just before collision and that just after collision are the same.
(2)
The speed of the ball just before collision and that just after collision are the same.
(3)
The net force acting on the ball during the downward journey and that during the upward journey are same.
A.
(1) and (2) only
C.
(1) and (3) only
B.
(2) and (3) only
D.
(1), (2) and (3)
A ball is projected upwards at an angle of 30° with the horizontal from the top of a cliff at a speed of 20 m s1. Assume that
there is no air resistance. What will be the vertical displacement of the ball 5 s later? Take the acceleration due to gravity as
9.81 m s2.
A.
72.6 m upward
C.
173 m downward
B.
173 m upward
D.
72.6 m downward
6
22.
Two balls A and B are placed at the edge of a table. The mass of B is twice that of A. At the same instant, A is released from
rest while B is projected horizontally with speed u. Which of the following statements are correct? (Neglect air resistance.)
23.
(1)
A and B reach the ground at the same time.
(2)
A and B have the same acceleration.
(3)
A and B have the same vertical speed on reaching the ground.
A.
(1) and (2) only
C.
(1) and (3) only
B.
(2) and (3) only
D.
(1), (2) and (3)
A football is projected upwards at an angle to the ground. If air resistance is negligible, which of the below correctly
represent the horizontal and vertical velocities of the ball during its upwards flight?
24.
Horizontal velocity
Vertical velocity
A.
increase
unchanged
B.
increase
increase
C.
unchanged
decrease
D.
unchanged
increase
A particle is released from X. It rolls down a smooth curve to Y, a point at the edge of a platform of height 3 m. The particle
then leaves the platform horizontally and travels freely under gravity until it hits the ground at Z. The horizontal distance
between Y and Z is 5 m. Take the acceleration due to gravity as 10 m s2.
Find the vertical distance h.
25.
26.
A.
0.45 m
C.
2.08 m
B.
1.25 m
D.
4.17 m
When an object performs uniform circular motion, its velocity
A.
does not change.
B.
is changing all the time.
C.
does not have a direction.
D.
is always in the same direction.
When a plane makes a turning, it tilts so that
A.
air resistance is reduced.
B.
the plane can moves upwards.
C.
part of the lifting force provides the centripetal force.
D.
oil consumption is reduces.
7
27.
In the following figure, A and B are two identical balls. They are fixed on a rod and rotating with it. The distances of the
balls A and B from centre O are R1 and R2 respectively. What is the ratio of the angular speed of A to that of B?
O
R1
A
R2
A.
28.
11
B.
21
B
R2  R1
C.
R1  R 2
D.
A man is riding inside a ‘rotor’ of radius 3.5 m. The man rotates at an angular speed of 2.8 rad s–1. What is his centripetal
acceleration?
A.
29.
2.24 m s2
B.
9.80 m s2
27.4 m s2
C.
34.3 m s2
D.
A cyclist travels along a horizontal circular path of radius 25 m at a constant speed of 8 m s−1. The total mass of the cyclist
and his bicycle is 90 kg. What is the resultant force acting on the bicycle by the road surface?
A.
30.
929 N
B.
998 N
C.
1005 N
D.
1130N
In the following figure, a ball runs on a smooth rail from P to Q.
Which of the following graphs best represents the variation of the acceleration a of the ball with time t?
A.
C.
a
a
t
t
B
D.
a
a
t
t
8