The work required to accelerate an object initially at rest to a speed v f is W. What is the additional work needed to increase its speed from v f to 2 v f? W
W/2

2W

3W

none of them

11. you want to calculate the displacement of an object thrown over a bridge. using -10 m/s2 for acceleration due to gravity, what would be the total displacement of the object if it took 8 seconds before hitting the water?

Acoal-fired plant generates 600 mw of electric power. the plant uses 4.8 x 10^6 kg of coal each day, and the heat of combustion of coal is 3.3x 10^7 j/kg. the steam that drives the turbines is at a temperature of 300° c, and the exhaust water is at 37° c. (a) what is the overall efficiency of the plant for generating electric power? (b) how much thermal energy is exhausted each day? (c) what is the change in entropy of the universe for this heat engine? (d) using the same heat reservoirs, what is the maximum possible (carnot) efficiency for a heat engine?

Which of these has some mechanical energy? a. an atom b. heat inside earth c. a book on a shelf d. the fire from a lit match