A boy is at rest on a slide sloped at 22°. The coefficient of kinetic friction between the boy and the slide is 0.12. The boy starts down the slide. What is the acceleration?

Amira pulls a 3 pound wagon 4 feet. how much work has she done?

4r-134a enters the condenser of a residential heat pump at 800 kpa and 50°c at a rate of 0.022 kg/s and leaves at 750 kpa subcooled by 3°c. the refrigerant enters the compressor at 200 kpa superheated by 4°c determine (a) the isentropic efficiency of the compressor, (b) the rate of heat supplied to the heated room, and (c) the cop of the heat pump. also, determine (d) the cop and rate of heat supplied to the heated room if this heat pump operated on the ideal vapor-compression cycle between the pressure limits of 200 and 800 kpa. (0.757, 4.37 kw, 5.12, 6.18, 3.91 kw)

How does the strength of the electrostatic force between an electron and a proton compare to the strength of the gravitational force between them?