c @ * 12%) 0.+ 11:38 PM webwork.phys.yorku.ca No SIM Previous Problem List Next

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c @ * 12%) 0.+ 11:38 PM webwork.phys.yorku.ca No SIM Previous Problem List Next (1 point) THE PROBLEM You have heard people say that the angular momentum of its wheels helps a bicycle to stay upright. To gather more information, you decide to design a bicycle wheel that will have only 3/4 of the angular momentum of the original bicycle wheel when both wheels are travelling along a road at the same velocity. The original wheel had a diameter of di -36 cm and a rotational inertia of 11 =0.31 m2 kg. If your new wheel has a diameter of d2 -33 cm, then what is its rotational inertia? PAPER SOLUTION INTERPRET DEVELOP EVALUATE ASSESS

Explanation / Answer

Angular momentum,L=(Rotational Inertia,I)*(Angular Velocity, w)

L=Iw

Original wheel,I=L/w =0.31kgm2

New wheel has only 3/4 th of the Angular Momentum of original wheel

So, New wheel, IN = 3/4(L/w)

= 3/4*0.31kg.m2

IN = 0.2325kg.m2

B.This is true.

Angular momentam, L=I*w

Rotational Inertia, I= Mass*r2

So when mass is less, rotational inertia decreases, so angular momentum also.

G. is true.

The wheels of a bicycle attain angular momentum when the bicycle is moving. Torque is applied to the back wheel by the pedals and chain to create a rotational acceleration. If the bicycle is moving in a straight line, the direction of the angular-momentum is equal for both wheels and is directed horizontal.

To tilt the bicycle, the direction of the angular-momentum must alter, and that needs a torque. When the bicycle is exactly straight, this force acts straight downward and passes through the axis of rotation for the falling bike. And the direction and magnitude of the original angular momentum are conserved.

By “right-hand rule,” the direction of that angular-momentum vector is along the axis and points forward or backward depending on the direction of tip. If the bike tilts to the left, the change in angular momentum points straight back.

The angular-momentum vector for each wheel is horizontal when the bicycle is upright.

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