Photo-Electric Effect, 0417, 28 minutes, $220.
ANSWERS TO PROBLEMS
First, mechanical energy drives the car’s electric generator. Second, the electrical energy is converted into chemical energy when the battery is recharged.
From the kinetic energy equation we get
v = √(2 E/m)
Since the engine is 25% efficient, the energy available to propel the car is 48,000 × 0.25 or 12,000 joules. So
v = √(24,000/1,000) = 2√6 = 4.9 meters per second
e = (300 - 20)/300 = 14/15 = 0.93 = 93%