A 100 kg person stands on a scale. a.) What would be the scale readout? N (How d

Question

A 100 kg person stands on a scale.

a.) What would be the scale readout?
N
(How does this compare with the person's weight?)

Now, find a general expression for the scale readout, in terms of the person's mass, acceleration, and/or g.
Show that it can be used to get the answer for part a above, and then use it to get the answers for all of the following parts:

b.) If the person stands on the scale in an elevator accelerating upwards at 7 m/s2, what is the scale readout?
N
(How does this compare with the person's weight?)

c.) If the person stands on the scale in an elevator accelerating downwards at 7 m/s2, what is the scale readout?
N
(How does this compare with the person's weight?)

d.) If the person stands on the scale in an elevator accelerating downwards at 9.8 m/s2, what is the scale readout?
N
(How does this compare with the person's weight?)

Explanation / Answer

a 100kg person stands on a scale? a.) What would be the scale readout? ___ N (How does this compare with the person's weight?) w = W - C = mg - mw^2r; where m = 100 kg, g = 9.81 m/sec^2, w = 2pi rad/24 hours [you need to change this to rad/sec], and r = R cos(L) Earth's radius of rotation at a given latitude L and the radius of Earth R. w is the net weight you are looking for, it's what you will read on the scale. In most daily problems, we can ignore centrifugal force C and set it to C = 0. If C = 0, the w = W = mg, which is the weight in Newtons. b.) If the person stands on the scale in an elevator accelerating upwards at 5 m/s2, what is the scale readout? ____N (How does this compare with the person's weight?) w = W + ma = mg + ma = m(g + a); where a = 5 m/sec^2. Is the net weight w greater or lesser than W? c.) If the person stands on the scale in an elevator accelerating downwards at 5 m/s2, what is the scale readout? ___N (How does this compare with the person's weight?) w = W - ma = m(g - a); again is w > W or ,

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