PHYSICS Unit 2MOMENTUM, WORK and ENERGY Revision 2008
Name:
On the grid below two displacement vectors, and , are drawn to scale, along with a sample of other vectors.
1Which vector best represents + ?
2Which vector best represents – ?
3A golfer is hitting a golf ball with a club whose head has a mass of 0.10 kg and a speed of 12 m s-1. Assume the mass of the club shaft is negligible. The momentum of the club head is
A 0.12 kg m/sB 1.2 kg m/sC 7.2 kg m/sD 12 kg m/s
4Immediately after contact with the golf ball the club head has a speed of 8.0 m s-1. Calculate the magnitude of the change in momentum of the club head.
A 0.4 NsB 0.8 NsC 1.2 NsD 2.0 Ns
5Photography shows that the club is in contact with the ball for 1.0 × 10-3 secs. Calculate the size of the average force acting on the golf ball during the collision.
A 400 NB 800 NC 1200 ND 2000 N
6If the mass of the golf ball is 2.5 × 10-2 kg. its speed immediately after being struck by the club must be
A 8 m/sB 12 m/sC 16 m/sD 20 m/s
7Which of the following would increase the speed of the golf ball as it leaves the club head if the change in the speed of the club head is the same as given above. (one or more answers)
AThe mass of the club head is decreasedB The mass of the golf ball is decreased
CThe mass of the club head is increasedD The mass of the golf ball is increased
A body of mass 2.0 kg is moving due west at 1.5 m s-1 when a force, the direction of which is also to the west, acts upon it for 4 secs. The diagram shows a graph of the variation of the force with time.
F (Newton)
6.0
3.0
0
1 2 3 4 t (second)
8What is the magnitude of the impulse exerted on the body in the first two seconds for which the force acts?
A 3 kg m s-1B 6 kg m s-1C 9 kg m s-1D 12 kg m s-1
9What is the magnitude of the total impulse exerted on the body by the force?
A 12 kg m s-1B 15 kg m s-1C 21 kg m s-1D 24 kg m s-1
Questions 10 and 11 refer to the following information.
A 0.50 kg ball travelling at 20 meast hits a wall and bounces back at a velocity of 16 m west. The ball is in contact with the wall for 2.5 s.
10What is the magnitude of the change in momentum of the ball?
A 2 NsB 8 NsC 10 NsD 18 Ns
11What is the magnitude and direction of the force exerted on the ball by the wall?
A 80 Ns eastB 80 Ns westC 720 Ns eastD 720 Ns west
Questions 12 to 14 refer to the following information.
A gardener is rolling a lawn with a hand roller as shown.
He pushes directly along the handle with a force of 100 N. The handle makes an angle of 45 to the horizontal.
The roller moves forwards at a constant speed of 1.5 m s–1.
It has a mass of 65 kg.
12How much work is done by the gardener in pushing the roller a distance of 5.0 m?
A 100 JB 150 JC 355 JD 500 J
13The magnitude of the force of friction acting on the roller is.
A 70 NB 100 NC 150 ND 500 N
14The kinetic energy of the roller is.
A 73 JB 113 JC 813 JD 1250 J
Questions 15 to 17 refer to the following information.
The following graph shows how force varies with compression for a spring.
The spring is compressed by 20 cm and it is used to horizontally propel a ball of mass 100 g. The ball starts from rest.
15How much elastic potential energy is stored in the spring when it is compressed by 20 cm?
A 0.016 JB 0.025 JC 1.6 JD 2.5 J
16What is the kinetic energy of the ball when the spring has returned to its original length?
A 0.016 JB 0.025 JC 1.6 JD 2.5 J
17What is the speed of the ball when the spring has returned to its original length?
A 0 m/sB 5.7 m/sC 8 m/sD 16 m/s
18A girl of mass 40.0 kg falls from rest a distance of 2.0 metres on to a trampoline. What is the kinetic energy of the girl as she lands on the trampoline?
A 800 JB 400 JC 80 JD 40 J
19An 800 kg car changes speed from 20 m s-1 to 15 m s-1. What is the decrease in the car's kinetic energy?
A 1 × 104 JB 5 × 104 JC 7 × 104 JD 9 × 104 J
Questions 20 to 22 refer to the following information
An astronaut carries a hammer on the moon. The hammer has a mass of 0.72 kg on Earth. On the moon, the acceleration of gravity is one sixth of its value on Earth. (On Earth, g = 10 m s-2)
20What is the mass in kilograms of the hammer on the moon?
A 0.12B 0.72C 1.20D 7.20
21What is the weight in Newtons of the hammer on the moon?
A 0.12B 0.72C 1.20D 7.20
22How much work must be done to raise the hammer through a vertical distance of 2.0 m on the moon?
A 1.2 JB 2.4 JC 7.2 JD 14.4 J
Questions 23 to 29 refer to the following information
The figure below represents a track which has been erected to demonstrate certain aspects of the energy of a body. A small cart of mass 4.0 kg moves without friction on the track, with a speed 10 m s-1 along AB
DE
2 m
AB
5 m
C
23What is the kinetic energy of the cart as it moves along AB?
A 20 JB 50 JC 100 JD 200 J
24At which point on the track is its kinetic energy at a maximum?
A AB BC CD D
25What is the change in potential energy of the cart between B and C?
A zeroB 20 JC 80 JD 200 J
26What is the change in potential energy of the cart between C and D?
A 20JB 80 JC 200 JD 280 J
27What is the change in potential energy of the cart between B and D?
A zeroB 20 JC 80 JD 200 J
28What is the kinetic energy of the cart as it moves along the horizontal level DE?
A zeroB 80 JC 120 JD 200 J
29What constant acceleration is required to stop the roller coaster at point E if the brakes are applied at point D?
A 2 m/s2B 4 m/s2C 6 m/s2D 10 m/s2