1 of 16

Motion and Time

Science

2 of 16

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

3 of 16

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.

4 of 16

POINTS TO REMEMBER

  • Measurement of time.

I. For measuring time our ancestor used sundials, water clocks and sand clocks.

5 of 16

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.

6 of 16

POINTS TO REMEMBER

  • Simple pendulum.
  • A simple pendulum consists of a small metallic ball called bob, suspended from a rigid stand by a thread.
  • 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.

7 of 16

POINTS TO REMEMBER

A

8 of 16

POINTS TO REMEMBER

Central Position

9 of 16

POINTS TO REMEMBER

B

10 of 16

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: Time

L: Length of Pendulum g: Gravitational Force

11 of 16

POINTS TO REMEMBER

  • Unit of time and speed
  • The basic unit of time is second. Its symbol is s or sec
  • The basic unit of speed is m/s
  • Speedometer. It is a device to record speed. It records the speed directly in km/h
  • Odometer. It is a device to measure the distance covered by the vehicle.

12 of 16

POINTS TO REMEMBER

13 of 16

POINTS TO REMEMBER

  • Graphical representation of data. We can represent the data in pictorial form by three ways
  • Bar graph
  • Pie chart
  • Line graph

14 of 16

POINTS TO REMEMBER

15 of 16

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.

16 of 16