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

Arefrigerator uses r-134a as the working fluid and operates on the ideal vapor-compression refrigeration cycle except for the compression process. the refrigerant enters the evaporator at 120 kpa with a quality of 34 percent and leaves the compressor at 70°c. if the compressor consumes 450 w of power, determine (a) the mass flow rate of the refrigerant, (b) the condenser pressure, and (c) the cop of the refrigerator. (0.00644 kg/s, 800 kpa, 2.03)