A 44.5-N weight is hung on a spring scale, and the scale is hung on a string. Th

Question

A 44.5-N weight is hung on a spring scale, and the scale is hung on a string. The string is

lowered at a rate such that the entire assembly has a downward acceleration of 9.80 m/s2

.

Now when I compute the equation  F=MA I end up with an approximation of 44.492 which is essentially the same as one of the answers posted.

here are the answers

The scale reads

(a) 0 N

(b) 22.2 N

(c) 44.5 N

(d) 66.7 N

(e) 71.2 N

Now my gut tells me 44.5N because  m =  44.5/9.8  and  (M)(A)=(4.54kg)(9.8m/s^2)  so by default I derive my answer. However my solutions provided by my teacher argues that the correct answer is  0 N  or  A.   and I can see how this might work  but it just doesn't seem to make sense. Maybe my teacher made an error? or perhaps it has something to do with adding an initial acceleration to a final acceleration to derive  0.

Explanation / Answer

m*g-W' =m*a

a = g ........so
the reading of the scale is

W' = m*(g-a) = m*g-m*a = m*g-m*g = 0

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