During a workout, a person repeatedly lifts a 16-lb barbell through a distance of 1.6 ft. How many "reps" of this lift are required to work off 150 C?

A 46-kg woman eats a 522 Calorie (522 kcal) jelly doughnut for breakfast. (a) How many joules of energy are the equivalent of one jelly doughnut? 2.19 Your response differs significantly from the correct answer. Rework your solution from the beginning and check each step carefully. J (b) How many steps must the woman climb on a very tall stairway to change the gravitational potential energy of the woman-Earth system by a value equivalent to the food energy in one jelly doughnut? Assume the height of a single stair is 15 cm. 3.22 X Your response differs significantly from the correct answer. Rework your solution from the beginning and check each step carefully. stairs (c) If the human body is only 26% efficient in converting chemical potential energy to mechanical energy, how many steps must the woman climb to work off her breakfast? 8.4 X Your response is off by a multiple of ten. stairs

If I add 12,183 J of energy to an ideal gas inside a balloon causing the internal energy to increase by 5185 J, how much work is done on the environment by the gas as the balloon expands?

As a gasoline engine is running, an amount of gasoline containing 18,500 J of chemical potential energy is burned in 1 s. During that second, the engine does 3,700 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?  %