How much work is done by a person lifting a 5.0-kg object from the bottom of a w

Question

How much work is done by a person lifting a 5.0-kg object from the bottom of a well at a constant speed of 2.0 m/s for 5.0 s? A) 0.22 kJ B) 0.34 kJ C) 0.49 kJ D) 0.57 kJ A force F acts on a particle as the particle moves along the x axis. If the particle's initial kinetic energy is 20.0 J and after 5 minutes its kinetic energy is 522 J, at what rate this force is doing work? A) 2.54 W B) 76.2 W C) 44.5 W D) 1.67 W The only force acting on an object as it moves along the positive x axis is F_x = 8x, where x is in meters. What is the net change in its Kinetic energy as it moves from x = -1 m to x = 4 m A) 60 J B) 49 J C) 19J D) 17 J

Explanation / Answer

ANSWER:

10)C) 0.49KJ

Explanation:

Work done is equal to the force moved and the distance moved. In your case, it has been made slightly more difficult by giving you what is needed to calculate the components of the work equation and then, therefore, the work done.

So:

W = F x d

From your formula list, F = mass (m) x gravity (g), and that d = speed (s) x time (t).

So we can rewrite the work formula as:

W = mg x st
W = (5.0 x 9.81) x (2.0 x 5.0)
W = 49.05 x 10
W = 0.49KJ  

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