You use a quantity of fuel with a total energy content of 19.02 MJ to power an engine. If the average output of the engine over 2 hours was 2.12 kW,  what is the efficiency of the engine?

Suppose you spend 30.0 minutes on a stairclimbing machine, climbing at a rate of 90.0 steps per minute, with each step 8.00 inches high. If you weigh 150 lb and the machine reports that 600 kcal have been burned at the end of the workout, what efficiency is the machine using in obtaining this result? If your actual efficiency is 0.18, how many kcal did you actually burn?

As a gasoline engine is running, an amount of gasoline containing 13,600 J of chemical potential energy is burned in 1 s. During that second, the engine does 3,400 J of work. (a) What is the engine's efficiency (in percent)? % (b) The burning gasoline has a temperature of about 4,100°F (2,500 K). The waste heat from the engine flows into air at about 90°F (305 K). What is the Carnot efficiency (in percent) of a heat engine operating between these two temperatures? Need Help? % Read It

A Carnot engine uses a hot reservoir consisting of a large amount of boiling water and a cold reservoir consisting of a large tub of ice and water. When 6442 J of heat is put into the engine and the engine produces work, how many kilograms of ice in the tub are melted due to the heat delivered to the cold reservoir? Do not enter unit.

The engine of a large ship does 1.97  1010 J of work with an efficiency of 8.60%. (a) How much waste heat is produced? (b) How many barrels of fuel are consumed if each barrel produces 6.00  109 J of heat when burned?

A heat pump removes 2060 J of heat from the outdoors and delivers 3060 J of heat to the inside of a house. (a) How much work does the heat pump need?(b) What is the coefficient of performance of the heat pump?

A large electrical power station generates 1050 MW of electricity with an efficiency of 37.0%. (a) Calculate the heat transfer (in J) to the power station, Q, in one day. (b) How much heat transfer Q. (in J) occurs to the environment in one day? (c) If the heat transfer in the cooling towers is from 35.0°C water into the local air mass, which increases in temperature from 18.0°C to 20.0°C, what is the total increase in entropy (in J/K) due to this heat transfer? J/K (d) How much energy (in J) becomes unavailable to do work because of this increase in entropy, assuming an 18.0°C lowest temperature? (Part of Q. could be utilized to operate heat engines or for simple space heating, but it rarely is.) to Additional Materials O Reading CS Scanned with CamScanner

Suppose that a heat engine takes 3.20  104 J of heat from the high-temperature reservoir to produce 1.90  104 J of mechanical work. (a) What is the efficiency of this engine?   (b) How much waste heat does it produce?

A freezer has a coefficient of performance of 6.30. The freezer is advertised as using 433 kW-h/y. Note: One kilowatt-hour (kW-h) is an amount of energy equal to operating a 1-kW appliance for one hour. (a) On average, how much energy does the freezer use in a single day? J (b) On average, how much thermal energy is removed from the freezer each day? J (c) What maximum amount of water at 17.0°C could the freezer freeze in a single day? (The latent heat of fusion of water is 3.33 ✕ 105 J/kg, and the specific heat of water is 4186 J/kg · K.) kg

An electric motor has its shaft coupled to that of an electric generator. The motor drives the generator, and some current from the generator is used to run the motor. The excess current is used to light a home. What is wrong with this scheme?