Page 123 - SCERT Kerala State Syllabus 8th Standard Basic Science Textbooks English Medium Part 1_Neat

Time taken bqWn‰v kabØn¬
Total distance Distance travelled Displacement
Displacement for the AYhm Hcp
Stages of journey travelled in per second per second
in metre (m) journey in sk°‚n¬ D≠mb
metre (m) (in unit time) (in unit time)
second (s) ÿm\m¥cw

On reaching the
office
On reaching back
home.
Table 9.5
Displacement is the
Speed is the distance travelled in unit time.
straight line distance from
the initial position to the Velocity is the displacement in unit time.
final position, irrespective Write down the equation for velocity,
of the path taken. While if speed = distance/time.
calculating velocity this
Is the velocity and speed equal, while travelling from home
straight line distance itself
is the displacement, even to office?
if it is not the actual path In which unit is speed expressed? What about velocity?
taken. But the time taken
What is the speed with which the person travelled?
to cover the actual
distance should be used What is his velocity as he reaches home?
for the calculation. Velocity is a vector quantity. What do you think speed is?

Observe the depiction of the path taken by an object as it moves
from A to C through B (Fig.9.6).

Calculate the speed and velocity of the object.
B

60 m 4s 40 m
6s
C
Nautical mile A 70 m
Fig. 9.6
Nautical mile is the unit for
Find out the situation in which the magnitude of speed
measuring the distance in the
field of aviation and sea and velocity become equal and write it down .
transportation. One nautical Tabulate the differences between speed and velocity.
mile is 1.852 km. The unit for
measuring the speed of
Sl.
aeroplanes and ships is knot. Speed Velocity
No.
One knot is the speed taken
to travel one nautical mile in 1 Scalar quantity Vector quantity
one hour. 2
Table 9.6
122 Basic Science VIII