Explain how to solve and then answer the following questions:

Question 1:

Eating 2500 Cal every day a friend of mine maintains a stable weight of 70 kg. One day, after eating 3500 Cal, he decided to do extra exercise to avoid gaining weight. He was doing jumps: he leaves the ground with a speed of 3.3m/s at every jump. Assuming that his body turns energy to mechanical work with a 25 % efficiency, how many jumps he will have to make?A metal sphere of 0.5 kg is heated to 3'31} \"C: than dropped into a beaker holding LUBE kg mercury at 20 \"C. The temperature of the mercurj,r stabilizes at 99C after a couple of minutes. What metal was the sphere made of? At constant 400 kPa pressure a gas is compressed from 600 cm to 200 cm', while 100 J of heat energy transferred from the gas to its surrounding. How much has the gas thermal energy changed