Q1. A 4.00 kN piano is lifted by three workers at the constant speed to an apartment 20.9 m above the street using a pulley system fastened to the roof of the building. Each worker is able to deliver 143 W of power, and the pulley system is 75.0 percent efficient (so that 25.0% of the mechanical energy is lost because of friction in the pulley). Neglecting the mass of the pulley, find the time required to lift the piano from street to the apartment.

Q2. A young woman buys a sports car that can accelerate at the rate of 5.47m/s2. She decides to test the car by drag racing with another speedster, Stan Speedy. Both start from rest, but experienced Stan leaves the starting line 1.47s before Kathy. Stan moves with a constant acceleration of 3.65 m/s2 and Kathy maintains the acceleration of 5.47m/s2.
Find the time it takes Kathy to overtake Stan.