Motion in a Plane
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Question : 9
Total: 32
A cyclist starts from the centre O of a circular park of radius 1 km, reaches the edge P of the park, then cycles along the circumference, and returns to the centre along QO as shown in figure. If the round trip takes 10 min, what is the (a) net displacement, (b) average velocity, and (c) average speed of the cyclist?
Solution:
(a) Net displacement is zero as both initial and final positions are same.
(b) Average velocity=
As displacement is zero, average velocity of the cyclist is also zero.
(c) Average speed=
=
Now, OP = QO = 1 km;
P Q =
( 2 π r )
=
( 2 π × 1 )
= 1.571 k m t = 10 min
=
h =
h
∴ =
= 3.571 × 6 = 21.43 k m h − 1
(b) Average velocity
As displacement is zero, average velocity of the cyclist is also zero.
(c) Average speed
Now, OP = QO = 1 km;
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