Calculate Net Work Done by Fpush, Fgrav, Fnormal - 5N, 5m

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The discussion focuses on calculating the net work done by different forces acting on a book pushed up a ramp. The net work done by the pushing force (Fpush) is correctly calculated as 25 J using the formula W = Fd. Participants seek clarification on the work done by gravitational force (Fgrav) and normal force (Fnormal), emphasizing the importance of the angle between the force and displacement in these calculations. It is noted that work is only done when the force acts in the direction of displacement, and the angles for Fgrav and Fnormal need to be analyzed for accurate results. The conversation also briefly touches on a separate example involving work done in a tug of war scenario.
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A book is pushed up a ramp by a force. Calculate the net work done by :

a. Fpush
b. Fgrav
c. Fnormal

Let fnet = 5 Newtons and displacement of the object be 5 m up the ramp,
so the net work done by Fpush = 5 * 5 = 25 J. is the Work net by grav = mgsin@ * 5? and net work by Fnormal = mgcos@ * 0.5? is the work of gravity negative and Fnormal positive? Kindly guide me to the correct answers. Thanks
 
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Fpush is right. For part b and part c. You do need to understand that the work is done only by multiplying the force and the distance parallel to the direction of the force.
 
sundeepsingh said:
A book is pushed up a ramp by a force. Calculate the net work done by :

a. Fpush
b. Fgrav
c. Fnormal

Let fnet = 5 Newtons and displacement of the object be 5 m up the ramp,
so the net work done by Fpush = 5 * 5 = 25 J. is the Work net by grav = mgsin@ * 5? and net work by Fnormal = mgcos@ * 0.5? is the work of gravity negative and Fnormal positive? Kindly guide me to the correct answers. Thanks
Keep in mind that Work is a dot product of the force and displacement vectors. So:

W = Fd\cos\theta

So for c. what is the angle between the force and the displacement? What is the cos of that angle?

For b, what is the angle between the gravitational force and the displacement in terms of \alpha, the angle of the ramp above the horizontal? (your answer is right here, but the analysis is not clear).

You have it right for a.

AM
 
could you please answer this?
During a tug of war, team A pulls on team B by applying a force of 1100 Newton to the rope between them. How much work does team A do if they pull team B toward them in a distance of 2 meters?
 
eureka360 said:
could you please answer this?
During a tug of war, team A pulls on team B by applying a force of 1100 Newton to the rope between them. How much work does team A do if they pull team B toward them in a distance of 2 meters?

The answer to your question is in Andrew Mason's post above. :smile:
 

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