TIME AND MOTION-REVISION

TIME AND MOTION-REVISION

Measurement of Time in Ancient Times

The time taken between one sunrise to the next sunrise -solar day

The time taken between one new moon to the next new moon -Month

The time taken by the earth to complete one revolution of the sun -year

PERIODIC MOTION

• A motion which repeats itself at regular intervals of time is called periodic motion

• common device : Simple Pendulum

SIMPLE PENDULUM

• A simple pendulum consists of a metal bob suspended by a long thread from a rigid support

• Motion of pendulum was first studied by GALILEO

Terms related to Simple Pendulum

• Length : the length of the string from point of suspension to the centre of bob

• Mean Position of the bob: The position of the bob when it is at rest

• Oscillation of the pendulum: One complete to and fro motion of the bob about its mean position

• Amplitude of the pendulum: The maximum displacement of the bob from its mean position on either side

• Time Period: The time taken by the bob of a pendulum to complete one oscillation

• Frequency of the pendulum: The number of oscillations made by a pendulum in one second

•  $\frac{\frac{1}{time\ period\ \left[T\right]}}{ }$  = Frequency 

Multiple Choice

the time taken between one sunrise to next sunrise

• solar day

• night

• week

Multiple Choice

The time taken between from one new moon to the next new moon

• new moon

• half moon

• day

• month

Poll

A device which shows periodic motion

• Simple pendulum

• wrist watch

Multiple Choice

Which time measuring device was not used in ancient time ?

• sundial

• Quartz watch

• sand clock

• water clock

Open Ended

A simple pendulum takes 36 seconds to complete 20 oscillations .What is the time period of this pendulum?

Open Ended

The time period of the pendulum is 25 seconds. find its frequency.