Grade 12
PHYSICAL SCIENCES
Term 1
Vertical Projectile Motion
QUESTION 1
Various options are provided as possible answers to the following questions. Choose the
answer and write only the letter (A-D) next to the question number (1.1- 1.3) in the
answer sheet, e.g. 1.1 A.
1.1 A ball is projected vertically upwards from the ground. It returns to the ground,
makes an elastic collision with the ground and then bounces to a maximum
height. Ignore air resistance. Which ONE of the following velocity-time graphs
CORRECTLY describes the motion of the ball?
1.2 The statements below describe the motion of objects.
(i) A feather falls from a certain height inside a vacuum tube.
(ii) A box slides along a smooth horizontal surface at constant speed.
(iii) A steel ball falls through air in the absence of air friction.
Which of the following describes UNIFORMLY ACCELERATED motion
CORRECTLY?
A (i) and (ii) only
B (i) and (iii) only C
(ii) and (iii) only
D (i), (ii) and (iii) (2)
1.3 An object is thrown vertically upwards. Which ONE of the following regarding the
object’s velocity and acceleration at the highest point of its motion is
CORRECT? Ignore the effects of friction.
VELOCITY ACCELERATION
A Zero Zero
Zero
Maximum
B Upwards
C Zero
D Zero Downwards
(2)
[6]
QUESTION 2
A boy projects a ball of mass 0, 5 kg vertically downwards towards the ground from a height
-1
of 1,8m at a velocity of 8 m·s . The ball is in contact with the floor for 0, 01 s. Ignore the
effects of air friction.
1,8m
GROUND
2.1 The boy claims that the ball was in a free fall directly after he projected it. Do you
AGREE or DISAGREE with his statement?
Give a reason for your answer. (2) 2.2 Draw a free body diagram for an object in
free fall. (1)
2.3 Write down the magnitude and direction of the acceleration of the ball immediately after
it is projected. (1)
2.4 Calculate:
2.4.1 The magnitude of the velocity with which the ball hits the
ground. (4) 2.4.2 The time it takes the ball to hit the ground. (3) 2.4.3 The
net force exerted by the ball on the ground. (3)
2.5 Sketch an acceleration-time graph for the motion of the ball (no values required). (2) [16]
QUESTION 3
The diagram below shows the motion of a stone that is thrown vertically upwards from the
-1
roof of a 5,83m high building at a velocity of 4,9 m.s . After reaching the highest point
above the roof, it falls past the roof and strikes the ground after 1,7s from the start of its
motion.
5,83m
3.1 Define the term projectile. (2) 3.2 Calculate, using the equations of motion:
3.2.1 The time taken for stone to reach its maximum height. (3) 3.2.2 The velocity
with which the stone reaches the ground. (3) 3.2.3 The maximum height the stone
reached above the ground. (3)
3.3 Sketch a velocity-time graph for the motion of the stone, from the time the
stone is thrown until it hits the ground.
Clearly show the following on the graph:
∙ The initial velocity of the stone.
∙ The velocity and time when the stone hits the ground.
∙ The time taken by the stone to reach the maximum height. (4) [15]
QUESTION 4
A ball of mass 0, 2 kg is dropped vertically downwards from the top of a building to a
concrete floor below. The ball bounces off the floor. The velocity versus time graph below
shows the motion of the ball. Ignore the effects of air friction. TAKE DOWNWARD
MOTION AS NEGATIVE.
4.1 Use the graph only:
4.1.1 To determine the number of times the ball bounces off the floor. (1)
4.1.2 To determine whether the collision between the ball and the floor is elastic or
inelastic. Provide a reason for your answer. (2)
4.1.3 To calculate the height from which the ball is dropped. (3)
(3)
4.2 Calculate the impulse that the ball exerted on the floor when it struck the
floor for the first time.
4.3 Sketch a POSITION versus TIME graph for the motion of the ball from the
moment it was dropped until time t. USE THE POINT WHERE THE
BALL FELL FROM (i.e. the top of the building), AS THE ZERO
POSITION.
Indicate the following on the graph:
• The height from which the ball is thrown
• Time t (4) [13]
The end Total = 50 marks
DATASHEET
