9. Work & Energy

A $1000\mathrm{kg}$ pallet of bricks is being lowered to the ground by a crane. If the bricks are moving at a constant speed, how much work is done by the cable on the bricks as they descend $11\mathrm{m}$?

A particle of mass $250\mathrm{g}$ moving along the x axis has velocity $v_x=\left(7.6x^3\right)m/s$ with x measured in m. How much work is done on the particle as it moves from $\mathrm{x}=0.0\mathrm{m}$ to $\mathrm{x}=2.0\mathrm{m}$?

A factory worker pushes a 30.0-kg crate a distance of 4.5 m along a level floor at constant velocity by pushing horizontally on it. The coefficient of kinetic friction between the crate and the floor is 0.25. (e) What is the total work done on the crate?

Two tugboats pull a disabled supertanker. Each tug exerts a constant force of 1.80×106N, one 14° west of north and the other 14° east of north, as they pull the tanker 0.75 km toward the north. What is the total work they do on the supertanker?

A factory worker pushes a 30.0-kg crate a distance of 4.5 m along a level floor at constant velocity by pushing horizontally on it. The coefficient of kinetic friction between the crate and the floor is 0.25. (d) How much work is done on the crate by the normal force? By gravity?

A factory worker pushes a 30.0-kg crate a distance of 4.5 m along a level floor at constant velocity by pushing horizontally on it. The coefficient of kinetic friction between the crate and the floor is 0.25.(b) How much work is done on the crate by this force?