Page 97 - Understanding NCERT Science 09

(a) Which of the three is travelling the fastest?
(b) Are all three ever at the same point on the road?
(c) How far has C travelled when B passes A?
(d) How far has B travelled by the time it passes C?
7. A ball is gently dropped from a height of 20 m. If its velocity
increases uniformly at the rate of 10 m s , with what velocity
-2
will it strike the ground? After what time will it strike the
ground?
8. The speed-time graph for a car is shown is Fig. 7.11.

Fig. 7.11
(a) Find how far does the car travel in the first 4 seconds.
Shade the area on the graph that represents the distance
travelled by the car during the period.
(b) Which part of the graph represents uniform motion of
the car?
9. State which of the following situations are possible and give
an example for each of these:
(a) an object with a constant acceleration but with zero
velocity
(b) an object moving with an acceleration but with uniform
speed.
(c) an object moving in a certain direction with an
acceleration in the perpendicular direction.
10. An artificial satellite is moving in a circular orbit of radius
42250 km. Calculate its speed if it takes 24 hours to revolve
around the earth.

86 SCIENCE

Rationalised 2023-24