Consider what happens when you jump up in the air. Which of the following is the most accurate statement?

1) It is the upward force exerted by the ground that pushes you up, but this force can never exceed your weight.

2) You are able to spring up because the earth exerts a force upward on you that is stronger than the downward force you exert on the earth.

3) When you push down on the earth with a force greater than your weight, the earth will push back with the same magnitude force and thus propel you into the air.

4) When you jump up the earth exerts a force F1 on you and you exert a force F2 on the earth. You go up because F1 > F2.

5) Since the ground is stationary, it cannot exert the upward force necessary to propel you into the air. Instead, it is the internal forces of your muscles acting on your body itself that propels the body into the air.

An internally reversible refrigerator has a modified coefficient of performance accounting for realistic heat transfer processes of where qin is the refrigerator cooling rate, qout is the heat rejection rate, and is the power input. show that copm can be expressed in terms of the reservoir temperatures tc and th, the cold and hot thermal resistances rt,c and rt,h, and qin, as where rtot rt,c rt,h. also, show that the power input may be expressed as 1.39 a household refrigerator operates with cold- and hot-temperature reservoirs of tc 5 c and th 25 c, respectively. when new, the cold and hot side resistances are rc,n 0.05 k/w and rh,n 0.04 k/w, respectively. over time, dust accumulates on the refrigerator’s condenser coil, which is located behind the refrigerator, increasing the hot side resistance to rh,d 0.1 k/w. it is desired to have a refrigerator cooling rate of qin 750 w. using the results of problem 1.38, determine the modified coefficient of performance and the required power input w under (a) clean and (b) dusty coil conditions. internally reversible refrigerator qout qin w high-temperature reservoir low-temperature reservoir th th,i tc,i tc high-temperature side resistance low-temperature side resistance w qin th tc qinrtot tc qinrtot copm tc qinrtot th tc

How are positive ions different from neutral atoms

Two waves maximally constructively interfere at a point in space. among the options below, select the possible value of their phase difference at that point in space.a. zerob. πc. π/2d. not determinable by the information provided