Question

Calculate the angular speed of a fly wheel making 120 revolution per minute .

Answer 1

angular speed of flywheel= 120° revolutions / min
( 1 revolution = 2π rad  , 1  min = 60s )
 
    w= 2nπ
       = 2π* 120÷60 rad /s 
       = 4π

Answer 2

As per the question, the fly wheel makes 120 revolutions per minute.

Hence, the frequency [f] of the wheel = 120 rev/min.

We are asked to calculate the angular velocity of the fly wheel.

The angular velocity of the fly wheel is calculated as -

                     $Angular\ velocity\ [\omega]\ =\ 2\pi f$

                                        ⇒  ω = 2× π×f

                                                  = 2×π×120 rad/min.

                                                  =240π  rad/min.    

  We know that 1 min. = 60 seconds

Hence the angular velocity of the wheel will be-

                                      $\omega\ =\ \frac{240 \pi} {60}\ rad/s$

                                          $=\ 4\pi \ rad/s$  [ans]