## Simple work question

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

 PhysOrg.com science news on PhysOrg.com >> Front-row seats to climate change>> Attacking MRSA with metals from antibacterial clays>> New formula invented for microscope viewing, substitutes for federally controlled drug
 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.

Recognitions:
Homework Help
 Quote by sundeepsingh 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