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gigi9

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1) A cable 600 ft long that weighs 4 lb/ft is hanging from a windlass. How much work is done in winding it up?

2) A 5-lbs monkey is attached to the end of a 30-ft hanging chain that weighs 0.2 lb/ft. It climbs the chain to the top. How much work does it do?

3) If R is the radius of the earth(about 4000 mi) and g is the acceleration due to gravity at the surface of the earth, then the force of attraction exerted by the Earth on a body of mass m is F=mgR^2/r^2, where r is the distance from m to the center of the earth. If this body weighs 100lb at the surface of the earth, what does it weigh at an altitude of 1000mi? How much work is required to lift it fromt eh surface to an altitude of 1000 mi?