The wheel of a motorcycle is of radius 35 cm. How many revolutions per minute must the wheel make so as to keep a speed of 66 km/h
Solution:
Given, radius of wheel of a motorcycle, r = 35 cm
Speed = 66 km/hr
We have to find the number of revolutions per minute.
One revolution of the wheel = circumference of wheel
Circumference = 2πr
= 2(22/7)(35)
= 44(5)
= 220 cm
Given, speed = 66 km/hr
1 km = 1000 m
1 hr = 60 min
Speed of the wheel in m/min = 66(1000)/60
= 11(100)
= 1100 m/min
1 m = 100 cm
Speed in cm/min = 1100(100)
= 110000 cm/min
Number of revolutions in one min = speed of the wheel / circumference of wheel
= 110000/220
= 10000/20
= 1000/2
= 500
Therefore, the number of revolutions per minute is 500.
✦ Try This: The wheel of a motorcycle is of radius 30 cm. How many revolutions per minute must the wheel make so as to keep a speed of 22 km/h?
Given, radius of wheel of a motorcycle, r = 30 cm
Speed = 22 km/hr
We have to find the number of revolutions per minute.
One revolution of the wheel = circumference of wheel
Circumference = 2πr
= 2(22/7)(30)
= (44/7)(30)
= 188.57 cm
Given, speed = 22 km/hr
1 km = 1000 m
1 hr = 60 min
Speed of the wheel in m/min = 22(1000)/60
= 22(1000)/6
= 366.667 m/min
1 m = 100 cm
Speed in cm/min = 366.667(100)
= 36666.667 cm/min
Number of revolutions in one min = speed of the wheel / circumference of wheel
= 36666.667/188.57
= 194
Therefore, the number of revolutions per minute is 194.
☛ Also Check: NCERT Solutions for Class 10 Maths Chapter 12
NCERT Exemplar Class 10 Maths Exercise 11.3 Problem 4
The wheel of a motorcycle is of radius 35 cm. How many revolutions per minute must the wheel make so as to keep a speed of 66 km/h
Summary:
The wheel of a motorcycle is of radius 35 cm. The number of revolutions per minute the wheel makes so as to keep a speed of 66 km/h is 500
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