Need hel plz 60 POINTS
4. A waiter carries a tray of food across a room. How much work was done on the tray?How do you know?

5. What is the equation for total mechanical energy?

6. Which of the following objects has more kinetic energy?

Explain your answer!!!
A 15 kg ball rolling north at 15 m/s

OR

A 15 kg ball rolling backwards at 7 m/s

Wo small variable-thrust jets are actuated to keep the spacecraft angular velocity about the z-axis constant at ? 0 = 1.16 rad/s as the two telescoping booms are extended from r1 = 1.18 m to r2 = 4.69 m at a constant rate over a period of 124 seconds. the small 19-kg experiment modules at the ends of the booms may be treated as particles, and the mass of the rigid booms is negligible. determine the necessary thrust t for each jet as a function of time where t = 0 is the time when the telescoping action is begun. after you have the general expression for t, answer the questions. show work.