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RD Sharma Solutions Class 7 Mathematics Solutions for Mensuration 2 Exercise 21.1 in Chapter 21 - Mensuration 2 Area of Circle
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A boy is cycling such that the wheels of the cycle are making 140 revolutions per minute. If the diameter of the wheel is 60 cm, calculate the speed per hour with which the boy is cycling.
Answer:
Given the diameter of the wheel = 60 cm
Distance covered by the wheel in 1 revolution = Circumference of the wheel
Distance covered by the wheel in 1 revolution = π d
= 22/7 × 60 cm
Distance covered by the wheel in 140 revolutions = 22/7 × 60 × 140
= 26400 cm
Thus, the wheel covers 26400 cm in 1 minute. Then,
Speed = 26400/100 × 60 m/hr
= 264 × 60 m/hr
= 264 × 60/1000 km/hr
= 15.84 km/hr
The speed with which the boy is cycling is 15.84 km/hr.
Video transcript
"hello students welcome to lido q a video
session
i am sef your science tutor and question
for today is
when is the body said to be at rest
a body is referred to be in the state of
rest or stationary when there is no
change in its position
so when the body doesn't change its
position with respect to its immediate
surrounding
we can say that it is at the rest
so this can be written as
a body
is referred
to be in state
of rest
when it
doesn't changes
its position
with respect
to its
immediate
surroundings so this is our answer
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