1. Consider a car with a 25%-efficient engine that encounters an average retarding force of 500 N. Assume that the energy content of the gasoline is 40 MJ/L. Show that the car will get 20 km per liter...

1. Consider a car with a 25%-efficient engine that encounters an average retarding force of 500 N. Assume that the energy content of the gasoline is 40 MJ/L. Show that the car will get 20 km per liter of fuel.

2. When a cyclist expends 1000 W of power to deliver mechanical energy to her bicycle at a rate of 100 W, show that the efficiency of her body is 10%.