AQA P2 Physics GCSE - Key points

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AQA Physics Unit 2 ­ Key Points
1.1 Distance Time Graphs
The distance-time graph for any object that is
- Stationary is a horizontal line
- Moving at a constant speed is a straight line that slopes upwards
The gradient of a distance-time graph for an object represents the object's speed.
Speed in metres per second, m/s =
distance travelled in metres, m
time taken in seconds, s
1.2 Velocity and acceleration
Velocity is speed in a given direction
Acceleration is change of velocity per second. The unit of acceleration is the metre per
second squared (m/s)
Acceleration = change of velocity
time taken
Deceleration is the change of velocity per second when an object slows down.
1.3 More about velocity-time graphs
If a velocity-time graph is a horizontal line, the acceleration is zero.
The gradient of a line on a velocity-time graph represents acceleration.
The area under the line on a velocity-time graph represents distance travelled (higher)
1.4 Using graphs
The speed of an object is given by the gradient of the line on its distance-time graph. (higher)
The acceleration of an object is given by the gradient of the line on its velocity-time graph.
The distance travelled by an object is given by the area under the line of its velocity-time graph.
2.1 Forces between objects
A force can change the shape of an object or change its motion or its state of rest.
The unit of force is the newton (N).
When two objects interact, they always exert equal and opposite forces on each other.
2.2 Resultant force
If the resultant force on an object is zero, the object stays at rest or at constant velocity. If
the resultant force on an object is not zero, the velocity of the object will change.
If two forces act on an object along the same line, the resultant force is:
1. their sum if the forces act in the same direction
2. their difference if the forces act in opposite directions
2.3 Force and acceleration
The bigger the resultant force on an object is, the greater its acceleration is.
The greater the mass of an object is, the smaller its acceleration is for a given force.
Resultant force (newtons, N) = mass (kilograms) X acceleration (metres/second2)

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Momentum is conserved whenever objects interact, provided the objects are in a closed
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