1. 5.4 Battle of the forces
09 January 2011
Unscramble the following words:
ntioricf
ceorf
ttaccon
iatvygr
rai srianstcee
ruthstup

2. Q Rearrange the letters to give some words
to do with mass and weight.
1 of 1
CEFOR
RIYTVAG
MAOIGLKR
WNOTEN
5.4 Battle of the forces
Starter question

3. Aims
• List forces that act on objects. [Level 4]
• Describe balanced and unbalanced forces.
[Level 5]
• Explain the consequences of unbalanced
forces acting on an object. [Level 6]

13. 5.4 Battle of the forces
Questions
1. What three things can happen to an object
if the forces acting on it are unbalanced?
2. Copy and complete the sentences below
using these words:
constant length balanced
directions still
When two forces are equal in size but opposite
in direction, they are called _______ forces.
If the forces on an object are balanced, it will
stay _______ or move at a _______ speed.
If forces are balanced, force arrows will be the
same _______ but point in opposite _______.
(Level 3)
(Level 3)
1 of 3

14. 5.4 Battle of the forces
Questions
3. Use a force arrow diagram to show a radio-
controlled car moving with a force of 3 N,
with a friction force of 1 N. Use a scale of
1 cm = 1 N.
4. If a car is speeding up and the engine force
is 250 N, what can you say about the size of
the air resistance and friction?
5. Why can the weight of a car and its engine
force never be balanced?
6. What do you think will happen to the speed
of a space ship if it turns off its engines in
space? Explain your answer.
(Level 4)
(Level 5)
2 of 3
(Level 6)
(Level 7)

15. 5.4 Battle of the forces
Questions
7. A sports car and a van that have the same
mass are travelling at the same speed. The
van’s engine needs to produce more force
than the car. Why is this?
(Level 7)
3 of 3