this is a presentatio to help my frnds of class 7 lz send thanks if you like it and downloaded at gaur.ankit98@gmail,.com

1. Motion and Time
Science

2. 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. 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. POINTS TO REMEMBER
 Measurement of time.
I. For measuring time our ancestor used
sundials, water clocks and sand clocks.

5. 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. 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.

7. POINTS TO REMEMBER
POINTS TO REMEMBER
A

8. POINTS TO REMEMBER
Central Position

9. POINTS TO REMEMBER
B

10. 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. POINTS TO REMEMBER
Unit of time and speed
I. The basic unit of time is second. Its symbol
is s or sec
II. 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. POINTS TO REMEMBER

13. POINTS TO REMEMBER
 Graphical representation of data. We can
represent the data in pictorial form by three
ways
I. Bar graph
II. Pie chart
III. Line graph

14. POINTS TO REMEMBER

15. 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.