1. P2.1 Forces and their effect
2.1.1 Resultant forces
2.1.2 Forces and motion
2. Forces can cause changes to the shape or motion
of an object. Objects can move in a straight line at a
constant speed. They can also change their speed
and / or direction (accelerate or decelerate). Graphs
can help us to describe the movement of an object.
These may be distance–time graphs or velocity–
time graphs.
3. You should be able to:
■ interpret data from tables and graphs relating to speed,
velocity and acceleration
■ evaluate the effects of alcohol and drugs on stopping
distances
■ evaluate how the shape and power of a vehicle can be
altered to increase the vehicle’s top speed
■ draw and interpret velocity–time graphs for objects that
reach terminal velocity, including a consideration of the
forces acting on the object
4. Key words
Force
Motion
Resultant
Stationary
Velocity
Acceleration
Mass
Gradient
Speed
Stopping distance
Reaction time
Friction
Kinetic energy
Terminal velocity
Elastic
Potential energy
Work
Power
Momentum
Conservation of
momentum
5. If something is moving there is a force acting on it
To move something we need a force
A force is needed to change the shape of something
A force is a type of energy
Weight is a force
Mass is a force
Stretching a spring needs a force
A frictionless car does not need a force to keep it moving
Gravity is a type of force
Friction is a type of force
Forces always occur in pairs
6. P2.1.1 Resultant forces
a) Whenever two objects interact, the forces they exert on
each other are equal and opposite.
7. b) A number of forces acting at a point may be replaced
by a single force that has the same effect on the motion
as the original forces all acting together. This single
force is called the resultant force.
c) A resultant force acting on an object may cause a
change in its state of rest or motion.
8. d) If the resultant force acting on a stationary object is:
■ zero, the object will remain stationary
■ not zero, the object will accelerate in the direction of
the resultant force.
9. P2.1.2 Forces and motion
a) The acceleration of an object is determined by the resultant
force acting on the object and the mass of the object.
F = m × a
푎 =
퐹
푚
11. c) Calculation of the speed of an object from the
gradient of a distance–time graph.
d) The velocity of an object is its speed in a given
direction.
e) The acceleration of an object is given by the
equation:
푎 =
푣 − 푢
푡
12. f) The gradient of a velocity–time graph
represents acceleration.
13. g) Calculation of the acceleration of an object from the
gradient of a velocity–time graph.
h) Calculation of the distance travelled by an object from
a velocity–time graph.
