Question

The wheel of a cycle is of radius 35 cm. how many revolutions per minute must the wheel make so as to keep a speed of 66 km / hr?

Answer 1

Hi ,

Radius of the wheel = r = 35 cm

Distance travelled by 1 revolution

= Circumference of the wheel

= 2πr

= 2 × ( 22/7 ) × 35

= 220 cm----( 1 )

Speed = 66km/ h

= 6600000 cm / 60 minutes

= 110000 cm / mi


Therefore ,

220 cm travelled in 1 revolution

Let 110000cm travelled in x revolutions

x = 110000 / 220

x = 500

Number of revolutions = n = 500

I hope this helps you.

:)

Answer 2

Circumference of wheel=(2×22×35)÷7
=220cm=2.2m
Speed in m/s=66×5÷18
=55/3 m/s
Distance travelled in 1min(60sec) with 55/3 m/s speed=55×60÷3
=1100m
Revolution=distance/circumference
=1100/2.2
=500
Ans:500