# A Level PE - Linear Motion

- Created by: hotzmc
- Created on: 31-12-17 01:26

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A Level PE - Linear Motion:

Linear Motion:

Linear Motion: Movement of a body in a straight or curved line, where all parts move the same distance, in the same direction over the same time.

- E.g. A water skier on a flat lake being pulled at a constant speed will travel in a linear motion as all parts of their body will travel in the same direction over the same distance per unit of time
- Linear motion results from a direct force being applied to a body
- The force is likely being applied to the centre of a body’s mass (or centre of force)

Linear Motions Descriptors:

- Being able to describe motion is essential to analysing performance
- With the correct descriptors, calculations can be made assessing speed, velocity and acceleration over the whole, and different parts of an event
- E.g. 100m or the final 400m of a 5,000m
- This data can be used to analyse performance and help identify strengths and weaknesses

The 5 Key Descriptors:

- Distance
- Displacement
- Speed
- Velocity
- Acceleration/Deceleration

Distance:

Distance: The total length of the path covered from start to finish (or position A to position B)

- Distance is measures in metres (m)
- E.g. The distance covered in the 100m sprint is 100m, Swimming 4 lengths of a 50m pool is 200m

Displacement:

Displacement: The shortest straight line rout from start to finish (or Position A to Position B)

- Displacement is measured in metres (m)
- E.g. the displacement covered in a 100m race is 100m, swimming 4 lengths of a 50m pool is 0m

Speed:

Speed: The rate of change in distance (m/s)

- Speed = distance/time taken
- Speed is measured in metres per second (m/s), distance in metres (m) and time taken in seconds (s)
- E.g. If the speed of a runner in a 200m race is 21.63s, speed is calculated as 200m/21.63, so the average over the whole race is 9.25 m/s

Velocity:

Velocity: The rate of change in displacement (m/s)

- Velocity = displacement/time taken
- Velocity is measured in metres per second (m/s), displacement (m) and time taken (s)
- E.g. In a 100m race the displacement is 100m. It is run in 9.58s.
- Average velocity = 100m/9.58 = 10.44 m/s

Acceleration:

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