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

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Homework Help Overview

The discussion revolves around calculating the net work done by different forces acting on a book being pushed up a ramp. The forces in question include the applied force (Fpush), gravitational force (Fgrav), and normal force (Fnormal). Participants are exploring the relationships between these forces and the work done as the book is displaced along the ramp.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate the net work done by each force and questions the signs of the work done by gravity and the normal force. Some participants suggest focusing on the angles involved in the work calculations and the definition of work as a dot product of force and displacement vectors.

Discussion Status

Participants are engaged in clarifying the calculations for the work done by the forces involved. There is an acknowledgment of the need to understand the angles between the forces and displacement, and some guidance has been provided regarding the correct approach to calculating work.

Contextual Notes

There is a mention of specific angles related to the ramp and the forces, but the exact values or relationships are not fully established. The discussion also includes a separate query about a tug of war scenario, which appears to diverge from the main topic.

sundeepsingh
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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:

[tex]W = Fd\cos\theta[/tex]

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 [itex]\alpha[/itex], 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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