1. A ball falls from a height "h" from a tower. Which of the following statements is true? (20 Points)
the potential energy of the ball remains the same as it falls
the velocity of the ball is constant as it falls
the total kinetic and potential energy of the ball is constant (mechanical energy remains the same)
the kinetic energy of the ball remains the same as it falls

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?

If angle "a" is 25°, angle "b" is: a) equal to angle c b) less than angle c c) greater than angle c

The average density of the planet uranus is 1.27 103 kg/m3. the ratio of the mass of neptune to that of uranus is 1.19. the ratio of the radius of neptune to that of uranus is 0.969. find the average density of neptune.