Please solve this problem
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Please solve this problem

[From: ] [author: ] [Date: 11-10-02] [Hit: ]
Find the work done by machine on object. Is it positive or negative please explain.-Hmm..[0.Since it is free-falling,......
A machine project an object of mass 0.2 kg from some hight with initial speed of 3m/s. Find the work done by machine on object. Is it positive or negative please explain.

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Hmm..


[0.2kg]: initial speed= 3 m/s
:
: -H
:
: assuming the final velocity= 0 m/s

Since it is free-falling, the acceleration = 9.8 m/s^2

F = ma = 0.2 kg(-9.8 m/s^2) = -1.96 N

V(f)^2 - V(i)2 = 2ad
d = (v(f)^2 - v(i)^2)/2a = (0 m/s - (3 m/s)^2)/(2(-9.8 m/s^2) = -0.459 m

W = Fd = -1.96 N(-0.459 m) = 0.89964 kJ

The answer should be positive all the time. It depends on how you label your drawing.

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He may be referring to the fact that gravitational potential is negative energy. In fact, it exactly balances the mass-energy in the universe, and the net energy of the universe is null.

Yes, really. Google it yourself, smartass.

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Insufficient information.
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