Linear Motion

• Linear motion: movement of a body in a straight (or curved) line and all parts move the same distance, in the same direction, in the same time, e.g. Bobsleigh
• Linear motion is created through applying a direct force to the body.
• A direct force is an external force that is applied through the centre of mass.
• Distance is the length of a path between two points.
• Distance is measured in metres (m).
• Displacement is the shortest route between two points.
• Displacement is measure in metres (m).
• Speed is the rate of change in distance.
• Speed = distance/time
• Speed is measure is metres per second (ms^-1).
• Velocity is the rate of change in displacement.
• Velocity = displacement/time
• Velocity is measure in ms^-2.
• Acceleration is the rate of change of velocity.
• Acceleration = final velocity - initial velocity / time taken
• Acceleration is measure in ms^-2.
• Deceleration occurs when the rate of change of velocity is negative.
• Deceleration is measured in ms^-2.
• Always plot time on the x axis.
• The gradient of a distance/time graph represents the speed at a given time.
• The gradient of a speed/time graph represents the acceleration at a given time.
• In velocity time graphs, as you move away from the x axis velocity increases.
• In velocity time graphs, as you move closer to the x axis velocity decreases.
• In velocity time graphs, if you cross the x axis you change direction.