While Robert was helping his father in the garden, he pushed a shovel into the ground to dig a hole in the dirt. He picked up a shrub, carried it to the hole, and held it while he lowered it into the hole. During which parts of this process does Robert NOT do work? Choose the two statements that apply.
A. He pushed a shovel into the ground to dig a hole.
B. He picked up a shrub.
C. He carried it to the hole
D. He held it while he lowered it into the hole

Does work output exceed work input when a machine is used? a) yes, it does, as machines create energy. b) it depends on the type of machine used. c) no, it doesn’t, as machines are inefficient. d) no, it doesn’t, as machines cannot create energy.

A( developed during the process of technology design

Acommercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -35°c by rejecting waste heat to cooling water that enters the condenser at 18°c at a rate of 0.25 kg/s and leaves at 26°c. the refrigerant enters the condenser at 1.2 mpa and 50°c. if the compressor consumes 3.3 kw of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load, (c) the cop, and (d) the minimum power input to the compressor for the same refrigeration load.