Arturo O. answered • 02/24/17
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His mass is m, where m is in kilograms. His weight is
W = mg,
where g is the acceleration of gravity at sea level, which is 9.81 m/s2. Assume g is constant over the range of height in this problem. The height does not matter, unless it starts to approach the radius of the earth, in which case g is not constant, and a more complicated calculation is required.
Arturo O.
For a given mass m, the weight is the same at the height and at the bottom of the fall. The only way the weight can change is if the acceleration of gravity (g) changes. It does drop very slightly with increasing height, as the body is moved farther from the center of the earth. But for practical purposes, you can call g a constant 9.81 m/s2 from the surface of the earth up to a pretty high altitude.
Also keep in mind that the mass if 60 kg, not the weight. The weight is
(60 kg)(9.81 m/s2) = 588.6 N,
and it is the same at the top as at the bottom of the fall, unless the height from which it falls is comparable to the radius of the earth. But that is a different situation altogether. You can work these problems with a constant g.
Also, mass and weight are different things. Mass is the amount of matter the body has. Weight is the force of attraction on that mass due to the earth's gravitational field. If there was no gravitation, the body would still have mass, but no weight. Near the earth, it feels the gravitational force of the earth pulling it down toward the center of the earth, so it has both mass and weight.
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02/25/17
Ganesh L.
02/24/17