Physics - Rotation Question with Solution | TestHub
PhysicsRotationMiscellaneousMedium3 minQB
PhysicsMediumsingle choice
Passage / Comprehension
An exercise bike uses a heavy disc wheel. Two friction pads provide a total tangential retarding force of 20 N at 0.3 m from the wheel centre. The kinetic-friction coefficient is 0.4. The odometer distance is the distance travelled by a point 0.3 m from the centre. The pedals move in a circle of radius 0.15 m, and the transmission makes the wheel rotate twice per pedal revolution.
If the wheel has a kinetic energy of 30 J when the cyclist stops pedaling, how many rotations will it make before coming to rest ?
Options:
Answer:
A
Solution:
The retarding torque is 20×0.3=6 N m.
Work per rotation is τ·2π=12π J.
For 30 J, rotations=30/(12π), which is less than 1.
Stream:JEESubject:PhysicsTopic:RotationSubtopic:Miscellaneous
⏱ 3mℹ️ Source: QB
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