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
• 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.
• 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.
• 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.