physics help!!!!?

Question

A. A block with a mass m is pulled along a horizontal surface for a distance x by a constant force F at an angle with respect to the horizontal. Let M=2.00 kg , X= 4.00 m, angle= 37.0, F=15.0 N and Uk= 0.400

how much work is done by the friction force and by F???

Answer 1

Ok, first of all, you need to make a graphic. If yoy do that, you will see, that the block is moving to the right by the action of the force, that is making an angle of 37º respect to the horizontal.

Now, descompose the force, so you will have a value for the force in x, and a value for the force in Y.

Fx = 15*cos37 = 12 N

Fy = 15*sin37 = 9 N

Now, using g = 10 m/s^2 >>> gravity, the weight of the block will be :

the weight = 20 N

Now, analyzing in Y :

20 - Fy = Normal force

Normal force = 20 - 9 = 11 N

the force of friction = Normal force * Uk

then, the force of friction = 0.4*11 = 4.4 N

So, the work done by the friction in X = 4m will be :

4.4*4 = 17.6 Joules

If you wanna know the work donde by the force F, you just need to use the Fx, because it's an horizontal move:

Fx*x = work done by F

12*4 = 48 Joules