Question
Hard
Solving time: 4 mins
A cord of negligible mass is wound round the rim of a fly wheel of mass and radius . A steady pull of is applied on the cord as shown in Fig. The flywheel is mounted on a horizontal axle with frictionless bearings.
(a) Compute the angular acceleration of the wheel.
(b) Find the work done by the pull, when 2m of the cord is unwound.
(c) Find also the kinetic energy of the wheel at this point. Assume that the wheel starts from rest.
(d) Compare answers to parts (b) and (c).
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Text solutionVerified
(a) We use
the torque
Moment of inertia of flywheel about its
axis
angular acceleration
(b) Work done by the pull unwinding of the cord
(c) Let be the final angular velocity. The kinetic energy gained , since the wheel starts from rest. Now,
The angular displacement length of unwound string / radius of wheel
(d) The answers are the same, i.e. the kinetic energy gained by the wheel work done by the force. There is no loss of energy due to friction.
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A cord of negligible mass is wound round the rim of a fly wheel of mass and radius . A steady pull of is applied on the cord as shown in Fig. The flywheel is mounted on a horizontal axle with frictionless bearings.
(a) Compute the angular acceleration of the wheel.
(b) Find the work done by the pull, when 2m of the cord is unwound.
(c) Find also the kinetic energy of the wheel at this point. Assume that the wheel starts from rest.
(d) Compare answers to parts (b) and (c).
View all(a) Compute the angular acceleration of the wheel.
(b) Find the work done by the pull, when 2m of the cord is unwound.
(c) Find also the kinetic energy of the wheel at this point. Assume that the wheel starts from rest.
(d) Compare answers to parts (b) and (c).
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Question Text | A cord of negligible mass is wound round the rim of a fly wheel of mass and radius . A steady pull of is applied on the cord as shown in Fig. The flywheel is mounted on a horizontal axle with frictionless bearings. (a) Compute the angular acceleration of the wheel. (b) Find the work done by the pull, when 2m of the cord is unwound. (c) Find also the kinetic energy of the wheel at this point. Assume that the wheel starts from rest. (d) Compare answers to parts (b) and (c). |
Topic | System of Particles and Rotational Motion |
Subject | Physics |
Class | Class 11 |
Answer Type | Text solution:1 |
Upvotes | 119 |