## 2007-09-23

### Nota Fizik: Analysing linear motion

General Definition:

Distance: length between two points in a straight line or length moved through a definite path.

Displacement: Distance moved in a definite direction (vector quantity).

Speed: distance moved per unit time.

Velocity: rate of change in displacement.

Average speed: (total distance/total time)

Average velocity (total displacement/ total time)

Constant velocity: rate of change in displacement is constant (zero acceleration).

Positive acceleration means that the velocity is increasing.

Negative velocity means that the acceleration is negative and the velocity decreases.

Period, T, is the time taken for a complete oscillation. Unit: s-1

Frequency,f, is the number of oscillations made in one second. Unit: Hz

A ticker timer is used to measure a short period of time in linear motion. One dot is the period of time taken between two consecutive dots on a ticker tape. If the frequency used is 50 Hz, the period for one dot is then 0.02 s.

A stroboscope is used to 'freeze' the motion of an oscillation to determine its frequency, where frequency of the oscillation equals frequency of stroboscope.

Frequency of stroboscope = number of slits X frequency of rotation.