Solve problems involving work done by a force using 𝑊 = ∆𝐸 and 𝑊 = 𝐹𝑠.

A mechanic applies a constant horizontal force of 350 N to push a car 12 m across a workshop floor. The car's kinetic energy increases from zero to 2,800 J during this motion. Compare the work done by the applied force with the change in kinetic energy of the car, and identify what accounts for any difference.

A student conducts an experiment to determine the efficiency of a pulley system. A 2.5 kg mass is lifted through a vertical height of 1.8 m. The applied force required is 30 N, acting through a distance of 2.2 m along the rope. Energy is transferred to thermal energy in the pulley mechanism. a) Justify which equation for work (𝑊 = ∆𝐸 or 𝑊 = 𝐹𝑠) is most appropriate to calculate the useful energy output of the system. b) Determine the energy dissipated as thermal energy in the pulley. Show your reasoning.

A student pushes a 15 kg box across a horizontal floor with a constant horizontal force of 85 N. The box moves 4.2 m in the direction of the applied force. Friction acts on the box with a force of 62 N. State which equation for work is most appropriate to calculate the net work done on the box, and justify your choice.

A block is pulled along a horizontal surface by a constant horizontal force of 150 N. The block moves 8.0 m in the direction of the force. Calculate the work done on the block by the applied force.