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RP8-1) When calculating the work done on a body by a force, you need to add the work done by the force to the work done by the moment induced by the force.
RP8-2) Consider a rigid body undergoing general planar motion. The gravitational potential energy is determined by the height of what point on the rigid body?
RP8-3) When calculating the kinetic energy of a rigid body rotating about a fixed axis through a point O, you should use which of the following equations?
RP8-4) When a rigid body is rolling without slip on a stationary surface, the frictional force does work.
RP8-5) When a rigid body is rolling with slip the frictional force does work.
RP8-6) When a rigid body is rolling without slip on a conveyor belt, the frictional force does work.
RP8-7) If the external forces applied to a rigid body (or system of particles) sum to zero, then you are guaranteed that energy is conserved for the body (system).
RP8-8) A two-line bucket carries a load of dirt. The combined weight of the bucket and dirt is 1500 lb. A winch, weighing 20 lb and having a radius of 4 inches, lifts the bucket by applying a torque of M = 700 lb-ft. If the bucket starts from rest and the winch has a radius of gyration about its center of mass of k = 0.95 ft, determine the speed of the bucket when it has been hoisted 10 ft. Choose state 1 as defining zero potential energy.
RP8-9) The 50-kg slender bar shown has length l = 1 m and compresses a spring 11 centimeters when in the horizontal position. If the spring has stiffness k = 30 kN/m and the bar is released from rest in the horizontal position, then determine (a) the angular speed of the bar as it passes the angle θ = 45o and (b) the largest angle attained by the bar. Choose the hoizontal position as defining zero gravitational potential energy.
RP8-10) A manual push mower consists of an array of rotating cutting blades connected to a set of wheels (r = 10 in). To initiate motion, the operator applies a constant horizontal pushing force of P = 30 lb. If the wheel/blade assembly has a combined mass of 15 lb and a radius of gyration of kG = 0.5 ft and encounters a resistive moment of M = 10 lb-ft, determine the distance the mower travels before it reaches a velocity of 6 ft/s. The total weight of the mower is 50 lb. Assume that the handle angle remains constant and that the wheels roll without slip.
