Download HW8 - Bryn Mawr College

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7.3
Ring and bug*
A ring
m~ss M and radius R lies on its side on a frictionless
table. It 1S pivoted to the table at its rim. A bug of mass m walks
aro~d the rin~ with speed v, starting at the pivot. What is the
rotational velocity of the ring when the bug is
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. . (a) halfway around?
(b) back at the pivot?
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ear on a hill
A'3000~lb car is parked on a 30° slope, facing uphill. The center
or mass of the caris halfway between the front and rear wheels
and.is .2 ft above the ground. The wheels are 8 ft apart. Find the
normal force exerted by the road on the front wheels and on the
rear wheels.
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7.11 Wheel and shaft*
A wheel is attached to a fixed shaft, and the system is free to rotate
without friction. To measure the moment of inertia of the wheelshaft system, a tape of negligible mass wrapped around the shaft
is pulled with a known constant force F. When a length L of tape
has unwound, the system is rotating with angular speed woo Find
the moment of inertia 10 of the system.
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7.14
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Stick on table* ' .
A unif~rul stick of mass M and length I is. suspended horizontally
with ~ndB on the edge of a table, and the other end A is held by
hand.Point A. As; suddenly released. At the instant after release:
(a) What is die. torque around B?
(b) Whai is the 'angular acceleration around B?
(c)'What is the vertical acceleration of the center of mass?
(d)' F.ronl (c), find by inspection the vertical force at B.
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