Physics - Rotation Question with Solution | TestHub
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.
During a second workout, the cyclist reduces the force on the friction pads by 50%, then pedals for two times the previous distance in 1/2 the previous time. How does the amount of energy dissipated by the pads in the second workout compare with energy dissipated in the first workout ?
Options:
Answer:
Solution:
Dissipated energy is force times distance.
The pad force is halved while distance is doubled.
Their product is unchanged, so energies are equal.
