# P2

physics revision for aqa p2

- Created by: James Gillie
- Created on: 18-01-11 18:46

First 371 words of the document:

P2 Physics

Speed and Velocity

A time-distance graph plots distance travelled against the time taken

A slope on a time-distance graph represents speed, the steeper the slope the

greater the speed

o Speed = distance ÷ time

o Distance = speed x time

o Time = distance ÷ speed

Speed is measured in meters per second (m/s)

Velocity is a speed but with a given direction

This means that if a moving object changes direction then its velocity will change

even if its speed says the same

If the velocity we say the object is accelerating or decelerating

o Acceleration = change in velocity ÷ time taken for the change

Acceleration is measured in meters per second per second (m/s²)

A velocity-time graph plots the velocity against the time taken

The slope on a velocity time graph represents the acceleration or deceleration

The steeper the slope the greater the acceleration or deceleration

The area under the graph represents the distance travelled

We use the gradient of the line to work out the speed of an object, for example if

the graph shows it has moved 10 meters in 2 seconds then its speed is 5m/s

Speeding up and slowing down

We measure force in newtons (N)

Objects always exert equal and opposite forces on each other, these are often

referred to as action and reaction forces

Resultant force is where one single force will have the same effect than all the other

forces put together

When the resulting force is zero it means the object is stationary or is travelling at a

constant speed

If the resulting force is not equal to zero then it means the object is accelerating in

the direction of the resulting force

A resulting force always causes an acceleration, without acceleration the resulting

force must be zero

o Resulting force = mass x acceleration

The greater the resulting force the greater the acceleration

A vehicle travelling at a constant pace has a resulting force of zero which means the

all the driving forces are equal

## Comments

No comments have yet been made