The circuit of a motor racing tracks 3 km in length. In a race, a car goes 25 times round the circuit in 30 minutes.
What is the average speed of the car?
A 75 km/hour
B 90km/hour
C 150km/hour
D 750 km/hour

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?

Connie has $660,000 she wants to save. if the fdic insurance limit per depositor, per bank, is $250,000, which of these way is distributing her money between three banks will guarantee that all of her money is insured ?

An isotope undergoes radioactive decay by emitting radiation that has a –1 charge. what other characteristic does the radiation have?