Please help! Thank you! A 68.4-kg sky diver jumped out of an airplane at an altitude of 0.900 km. She opened her parachute after a while and eventually landed on the ground with a speed of 8.00 m/s. How much energy was dissipated by air resistance during the jump?

A 75-g bullet is fired from a rifle having a barrel 0.0660 m long. Choose the origin to be at the location where the bullet begins to move. Then the force (in newtons) exerted by the expanding gas on the bullet is 16,000+10,000x-24,000x2 where x is in meters. A) Determine the work done by the gas on the bullet as the bullet travels the length of the barrel (enter your answer to at least two decimal places.) B) If the barrel is 1.05 m long, how much work is done? (Enter your answer to at least two decimal places) C) How does this value compare with the work calculated in part A)? The work is greater by how much %?

9. A physics student decides to “burn off” some Calories by climbing a ladder. As the ladder is ascended, some food energy is being converted to gravitational potential energy. (a) If the student has a mass of 75 kg, how tall a ladder is needed to burn off one Calorie (4190 J)? (b) Conversely, if the student only has a 3.5 m ladder, how much additional mass must he carry up with him to burn off the Calorie?

An aluminium rod is 20 cm long at 20c and has a mass of 350 g. If 100000 j of energy is added to the rod by heat. What is the change in length of the rod?