Motion and TimeScience

POINTS TO REMEMBER

Speed. The movement of an object in a unit time is called its speed.

Speed is the distance covered divided by the time taken.

Speed = Distance covered/ Time Taken

POINTS TO REMEMBER

Non uniform motion. If the speed of an object moving along a straight line keeps changing its motion is said to be non uniform.

Uniform motion. An object moving along a straight line keeps changing its motion is said to be uniform motion. In this case, the average speed is the same as the actual speed.

POINTS TO REMEMBER

Measurement of time. I. For measuring time our ancestor used

sundials, water clocks and sand clocks.

POINTS TO REMEMBER

ii. The watches used today make use of periodic motion. One of the most well known periodic motion is that of a simple pendulum.

POINTS TO REMEMBER

Simple pendulum.I. A simple pendulum consists of a small

metallic ball called bob, suspended from a rigid stand by a thread.

II. When the bob of the pendulum is released after taking it slightly to one side it begins to move to and fro. The to and fro motion of a simple pendulum is an example of an oscillatory or a periodic motion.

POINTS TO REMEMBER

A

POINTS TO REMEMBER

POINTS TO REMEMBER

Central Position

POINTS TO REMEMBER

B

POINTS TO REMEMBER One Oscillation. The pendulum has said to have

completed ne oscillation when its bob moves from one extreme position A to the other extreme position B and comes back to A

Time period. Time taken by the pendulum to complete one oscillation is called its time period

Time period can be calculated by the relation T = 2∏√( L / g)

T: TimeL: Length of Pendulumg: Gravitational Force

POINTS TO REMEMBER

Unit of time and speedI. The basic unit of time is second. Its symbol

is s or secII. The basic unit of speed is m/sSpeedometer. It is a device to record speed. It

records the speed directly in km/hOdometer. It is a device to measure the

distance covered by the vehicle.

POINTS TO REMEMBER

POINTS TO REMEMBER

Graphical representation of data. We can represent the data in pictorial form by three ways

I. Bar graphII. Pie chartIII. Line graph

POINTS TO REMEMBER

POINTS TO REMEMBER

Motion of an object can be resented in pictorial form by their distance time graph.

I. The distance time graph for the motion of an object moving with a constant speed is always a straight line.

Presentation by Ankit Gaur