Home
Class 11
PHYSICS
A wheel rotating at an angular speed of ...

A wheel rotating at an angular speed of 20 rad/s ils brought to rest by a constant trouque in 4.0 secons. If the moiment of inertia of the wheel about the axis of rotation is 0.20 `kg-m^2` find the work done by the torque in the first two seconds.

A

10J

B

20J

C

30J

D

40J

Text Solution

Verified by Experts

The correct Answer is:
C
`omega_(1)= 20` rad/sec, `omega_(2)= 0, t= 4 sec`. So angular retardation `a = (omega_(1)- omega_(2))/(t)= (20)/(4)= 5 "rad"//sec^(2)`
Now angular speed after 2 sec `omega_(2)= omega_(1)- alpha t= 20-5 xx 2= 10` rad/sec
Work done by torque in 2 sec = loss in kinetic energy `= (1)/(2) I (omega_(1)^(2)- omega_(2)^(2))= (1)/(2) (0.20) ((20)^(2) - (10)^(2))`
`=(1)/(2) xx 0.2 xx 300= 30J`
Promotional Banner

Topper's Solved these Questions

  • ROTATIONAL MOTION

    ERRORLESS |Exercise Practice Problems (Problems based on centre of mass)|12 Videos

  • ROTATIONAL MOTION

    ERRORLESS |Exercise Practice Problems (Problems based on angular displacement, velocity and acceleration)|16 Videos

  • NEWTONS LAWS OF MOTION

    ERRORLESS |Exercise Self Evaluation Test|16 Videos

  • SIMPLE HARMONIC MOTION

    ERRORLESS |Exercise simple Harmonic Motion|21 Videos

Similar Questions

Explore conceptually related problems

A wheel rotating at a speed of 120 rpm about its axis is brought to rest by applying a constant torque for 4 s . Find the number of revolutions completed by the wheel before stop.

A flywheel rotating about a fixed axis has a kinetic energy of 360J when its angular speed is 30 radian s^(-1) . The moment of inertia of the wheel about the axis of rotation is

A fly wheel rotating about a fixed axis has a kinetic energy of 360 J . When its angular speed is 30 rad s^(-1) . The moment of inertia of the wheel about the axis of rotation is

A body rotating about a fixed axis has a kinetic energy of 360 J when its angular speed is 30 rad/sec. The moment of inertia of the wheel about its axis of rotation is

A wheel of mass 5 kg and radius 0.40 m is rolling on a road without sliding with angular velocity 10 rad s^-1 . The moment of ineria of the wheel about the axis of rotation is 0.65 kg m^2 . The percentage of kinetic energy of rotate in the total kinetic energy of the wheel is.

A constant net torque equal to 20 N-m is exerted on a pivoted wheel for 8 sec, during which time the angular velocity of the wheel increases from zero to 100 re // min. The external torque is then removed and the wheel is brought to rest by friction in its bearings in 70 sec. Compute (a) the moment of inertia of the wheel about the rotation axis, (b) the friction torque(c)thetotal no. of revolutions made by the wheel in the70 sec time interval

An autmobile moves on road with a speed of 54 km//h . The radius of its wheel is 0.45 m and the moment of inertia of the wheel about its axis of rotation is 3 kg m^(2) . If the vehicle is brought to rest in 15 s , the magnitude of average torque tansmitted by its brakes to the wheel is :

A torque of 100 N-m acting on a wheel at rest, rotates it through 200 radian in 10 s. What is the moment of inertia of the wheel?