4 Worksheet (AS)
Data needed to answer questions can be found in the Data, formulae and relationships sheet.
1
Two forces, each of magnitude 8 N, act on an object. The angle between the two forces is 60º.
What is the magnitude of the resultant force acting on the object?
A
B
C
D
2
The object in the diagram is in equilibrium.
Which equation is correct about the forces?
A
B
C
D
3
[1]
F
θ
15 = 20 cos θ
20 = F cos θ
F = 15 sin θ
F = 15 tan θ
15 N
0.5 m
100 N
200 N
300 N
400 N
A uniform square block is pushed along a
rough surface at constant speed by a force of
100 N. A horizontal force of friction acts
between the surface and the block.
What is the moment of the force of friction
about the centre of gravity?
[1]
A
B
C
D
[1]
2N
4N
6N
12 N
A man of weight 600 N stands at
the end of a uniform wooden
plank, which is pivoted as shown
in the diagram.
What is the weight of the wooden
plank?
[1]
A
B
C
D
5
20 N
A force of 10 N is resolved into two components at right angles to each other.
One of the components is 8 N. What is the other component?
A
B
C
D
4
4N
7N
8N
14 N
[1]
80 N m clockwise
80 N m anticlockwise
160 N m clockwise
160 N m anticlockwise
AS and A Level Physics
3.0 m
direction of movement
centre of
gravity
●
1.6 m
Original material © Cambridge University Press 2010
1
4 Worksheet (AS)
6 Calculate the magnitude of the resultant force in each case below.
a
b
[3]
[2]
7 In each case below, resolve the vector into two perpendicular components in the x and y directions.
a
b
[2]
[2]
8 a Define the moment of a force.
b State two conditions that must be met for the equilibrium of an extended object.
[1]
[2]
9 The diagram shows a uniform beam of
length 1.5 m and weight 60 N resting
horizontally on two supports.
a By taking moments about the support A, determine the force RB at the support B.
b Use your answer to a to calculate the force RA at support A.
[3]
[1]
10 A child of mass 35 kg on a swing is pulled to one side.
The diagram shows the forces acting on the seat of the
swing when it is in equilibrium.
a
What is the net force on the seat?
[1]
b Draw a triangle of forces. Hence determine:
i the tension T in the rope
ii the angle θ made by the rope with the vertical.
AS and A Level Physics
[4]
[2]
Original material © Cambridge University Press 2010
2
4 Worksheet (AS)
11 A gardener pulls a 50 kg roller along level
ground, as shown in the diagram.
The roller moves at a steady speed along
the level ground when the handle makes an
angle of 30° to the horizontal ground and
the gardener pulls with a force of 300 N
along the handle.
a Calculate the horizontal component of the force 300 N.
b What is the net force in the horizontal direction? Hence determine the magnitude of the
resistive force acting on the roller.
c Determine the vertical contact force acting on the roller due to the ground.
[2]
[2]
[3]
12 A ladder of mass 32 kg rests at an angle against a smooth
wall as shown in the diagram. The centre of gravity of the
ladder is at its mid-point.
a Determine the force R exerted by the wall on
the ladder by taking moments about the base
of the ladder.
[3]
b Explain why the force at the base of the ladder
was not included when doing the calculation in a. [1]
13 A 62 kg person lies flat on a uniform plank of mass 15 kg. The plank, with the person lying on it,
is placed on a brick and some bathroom scales, as shown in the diagram below.
The person’s toe-to-head distance is 1.56 m. The length of the plank is also 1.56 m.
a Sketch the diagram above. On your sketch, show all the forces acting on the plank.
b The reading on the bathroom scales is 30 kg. Use this information to determine how far
the centre of gravity of the person is from the toes.
Total:
AS and A Level Physics
45
Score:
Original material © Cambridge University Press 2010
[2]
[4]
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