作者stman (小強)
看板Physics
標題[題目] 求力大小
時間Thu Dec 26 08:58:15 2013
A drum has a radius of 0.40 m and a moment of inertia of 4.7 kg m^2.
The frictional torque of the drum bearings is 3.0 N m .
A ring at one end of a rope is slipped on a short peg on the rim of the drum,
and a 20-m length of rope is wound upon it. The drum is initially at rest.
A constant force is applied to the free end of the rope until the rope is
completely unwound and slips off the peg. At that instant,
the angular velocity of the drum is 16 rad/s.
The drum then decelerates and comes to a halt. In this situation, the
constant force applied to the rope is closest to?
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