Q. 25

# A flywheel of moment of inertia 5.0 kg-m2 is rotated at a speed of 60 rad/s. Because of the friction at the axle, it comes to rest in 5.0 minutes. Find (a) the average torque of the friction, (b) the total work done by the friction and (c) the angular momentum of the wheel 1 minute before it stops rotating.

The average torque is

The work done by the flywheel is

The angular momentum before stoppage of flywheel in 1 min is

Given

The moment of inertia of the flywheel is given as , the angular speed of the flywheel is given as 60 rad/sec and the time till it comes to rest is 5 minutes.

Formula Used

To find the average torque we use the formula as

For the calculation of work done from the torque of the flywheel

The angular momentum of the wheel is calculated as

where

L is the angular momentum, I is the moment of Inertia, ω is the angular velocity, W is the work done by the angular velocity, α is the angular acceleration and denotes the torque generated.

Explanation

First let us calculate the angular acceleration that will be

a) Now let us calculate the average torque of the flywheel which will be

The work done by the torque of the flywheel is

b) The angular momentum of the wheel in a time span of (5-1=4) minutes is

First let us find the angular velocity of the flywheel which is

Now placing the value of angular velocity in the formula of angular momentum we get the answer as

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Pseudo Force52 mins
Inelastic collisions in 1 D44 mins
Elaborative Lecture on Constraint Motion59 mins
A Lecture on Head-on Collision49 mins
NLM HCV Objective | Interactive Quiz63 mins
Questions Based on Equilibrium of a particle37 mins
Motion in 1 D38 mins
Newton Laws of Motion (Lecture 7)45 mins
Challenging Quiz on Newton Laws of Motion Part 364 mins
Moment of Inertia | Understanding the basics51 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses