Kinematics - Speed, Velocity, Acceleration

Velocity
- Change in distance in a specified direction per unit time
- Change in displacement per unit time

Displacement
- Distance in a specified direction

Acceleration
- Change in velocity with time
- SI Unit: metre per second per second
Positive Acceleration
- Change in velocity is in the same direction as the velocity
- Increasing speed
Negative Acceleration/Deceleration/Retardation
- Change in velocity is in the opposite direction to the velocity
- Decreasing speed

Acceleration = change in velocity / time taken

Speed Time Graphs

Increasing acceleration

Uniform acceleration
Constant acceleration
- Constant positive slope up
Constant deceleration
- Constant negative slope down
Non-uniform acceleration
Increasing acceleration
Decreasing acceleration

Decreasing acceleration

http://images.tutorvista.com/content/kinematics/increasing-acceleration.gif

http://images.tutorvista.com/content/kinematics/decreasing-acceleration.gif

Kinematics - Distance, Time, Speed

Speed
- Distance moved per unit time
- Average speed (Total distance travelled / Total time taken)
- Uniform speed (Constant)

Straight graph -> Object moving with uniform speed
Curved graph -> Object moving with non-uniform speed

Instantaneous speed
-> How fast an object is moving at a particular instant
-> Gradient of the tangent at a point n the distance-time graph

http://wps.prenhall.com/wps/media/objects/165/169061/GIFS/table1.5.gif
http://lgfl.skoool.co.uk/uploadedImages/SpeedTriangle.gif

U1 - Physical Quantities and SI Units

Physical quantities and SI units
Physical quantity
- Can be measured
- Consists of a numerical magnitude and a unit.
- Seven basic physical quantities/base quantities

Other physical quantities such as area, volume, speed are derived from these seven quantities. They are called derived quantities.


Measurement of Time
- Measured by observing events that are repeated
- Clocks and stopwatches can be used too