50 points for this worksheet

What is the efficiency of an engine that does 80 j of work and exhausts 320 j of heat while taking in 400 j of heat ? a. 10% b. 20% c. 80% d. 25%

Aheavy boy and a lightweight girl are balanced on a massless seesaw. the boy moves backward, increasing his distance from the pivot point. what happens to the seesaw? it is impossible to predict without knowing additional information. the side the boy is sitting on will tilt downward. the side the girl is sitting on will tilt downward. nothing; the seesaw will remain balanced.

9. an object is moved from the outdoors, which is at a temperature of 100 ºf, to a room at a temperature of 70 º f. what happens to the object when it’s placed in the room with a lower temperature? the object gives off more energy than it absorbs until it reaches a new lower thermal equilibrium where the amount of energy absorbed and given off is the same. the object gives off the same amount of energy as it absorbs until it reaches a new lower thermal equilibrium where the amount of energy given off is greater than the amount of energy it absorbs. the object gives off more energy than it absorbs until it reaches a new higher thermal equilibrium where the amount of energy absorbed and given off is the same. the object absorbs more energy than it gives off until it reaches a new lower thermal equilibrium where the amount of energy absorbed and given off is the same.