A3.0-kg object moves to the right at 4.0 m/s. it collides head-on with a 6.0-kg object moving to the left at 2.0 m/s.

which statement is correct?
a) the total momentum both before and after the collision is zero.
b) the total momentum both before and after the collision is 24 kg·m/s.
c) the total momentum before the collision is 24 kg·m/s, and after the collision is 0 kg·m/s.
d) none of the above is true.

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?

Explain how the energy of rubber ball is tranforned as it roll down a ramp. give evidence that the energy of the og the ball remains the same at all points on the ramp

Which of the choices below is one of the primary gases found in the atmosphere? a. helium b. carbon dioxide c. nitrogen d. argon