Q1. A 78.9 kg man steps off a platform 4.57 m above the ground. He keeps his legs straight as he falls, but at the moment his feet touch the ground his knees begin to bend, and, treated as a particle, he moves the additional 0.88 m before coming to rest. Treating our rigid legged friend as a particle, what is the average force his feet exert on the ground as he slows down?
Q2. A 150-V motor has mechanical power output of 3.70 hp. It is 83.0 percent efficient in converting power that it takes in by electrical transmission into mechanical power. If the electric company charges $0.110/kWh, what does it cost to run the motor for 2.12 h?