# Physics Unit 2

First two subjects forces and motion. From the AQA revision guide, physics.

- Created by: worker
- Created on: 09-12-12 18:07

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- Physics Unit 2
- Motion
- Distance Time Graphs
- Graphs can help describe the motion of an object.
- A distance Time Graph shows the distance of an object from a starting point against the time taken.
- The speed of an object is the distance travelled each second.
- The gradient of a line on a distance time graph represents speed.
- The steeper the gradient, the greater the speed.

- If an object is stationary on a distance time graph, the line is horizontal.
- If an object is moving at a constant speed the line on a distance time graph is straight that slopes upwards.
- The speed of an object can be calculated.
- Speed= Distance travelled/ time taken

- Velocity and Accelaration
- The velocity of an object is its speed in a given direction.
- if an object changes direction, it changes velocity even if the speed stays the same.
- If the velocity of an object changes we say it accelerates.

- if an object changes direction, it changes velocity even if the speed stays the same.
- Acceleration= (final velocity - initial velocity)/time taken for the change
- If the value for acceleration is negative the object is decelerating.
- Deceleration is the same as slowing down.
- It is the same as negative acceleration.

- Deceleration is the same as slowing down.

- The velocity of an object is its speed in a given direction.
- Velocity Time Graphs
- Velocity Time Graphs shows the velocity of an object against the time taken.
- The gradient of the line on a velocity time graph represents acceleration.
- The steeper the gradient the greater the acceleration.

- If the line on a velocity time graph is horizontal, acceleration is zero meaning the object is travelling at a steady speed.
- if the gradient of the line is negative then the object is decelerating.
- The area under the line on a velocity time graph represents the distance travelled in a given time.
- The bigger the area the greater the distance travelled.

- Distance Time Graphs

- Motion

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