A boy of mass 40kg is standing in the middle of a park. Questions;
a. Calculate his weight? Use acceleration due to
gravity=9.8m/^2. Direction should be indicated. 2 points
b. Referring to Newton's third law of motion, what does the boy's
weight represent (action or reaction force?)? 1 point
c. What is the boy's acceleration? 2 points
d. How much force is the boy exerting on the earth? Indicate the
direction. 2 points
e. Using the reaction force from d above, calculate the
acceleration of Earth as a result of the boy's weight.
(Estimated mass of earth in kg
5,973,600,000,000,000,000,000,000 kg) 3 points
f. As the boy stands there, he obviously does not feel the earth
moving/accelerating up towards him. Referring to appropriate
Newton's law, Explain why this is the case? 3 points

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

Aperson stands on a platform, initially at rest, that can rotate freely without friction. the moment of inertia of the person plus the platform is ip. the person holds a spinning bicycle wheel with its axis horizontal. the wheel has moment of inertia iw and angular velocity ωw. take the ωw direction counterclockwise when viewed from above. part a what will be the angular velocity ωp of the platform if the person moves the axis of the wheel so that it points vertically upward?

1.what is where an object is located 2. what is how fast an objects speed is changing 3. what is how fast an object is moving