Question

A string wound on the rim of a wheel 20cm in diameter is pulled out at rate of 75cm/s .through how many revaluations will the wheel have turned by the time that 9.0m of string has been unwound? How long will it take

Answer 1

Answer:

I have not understood the question

Answer 2

Answer:

Given : -

Diameter = 20 cm or 20 / 100 m => 0.2 m

So , Radius = Diameter / 2 = 0.1 m

Therefore ,

Circumference = 2 π r = 2π ( 0.1 ) = 0.2 π m

or , 0.2 × 3.14 = 0.628 m

Since , 9 m String has been unwound

So , No. of Revolutions

= Total length of String / Circumference

= 9 / 0.628 = 14 . 33

&

Since ,

Time = Distance / Speed

Time = 9 m / ( 75 cm / s )

Time = 9 × 100 cm / ( 75 cm / s )

Time = [ 9 × 4 / 3 ] sec . = 12 sec.