Have a stupid physics exam tomorrow. Been going over a problem that I cannot figure out and it's bothering me.

3. A horizontal force pulls a 13.6 kg box across the floor at constant speed. The coefficient of kinetic friction between the box and the floor is mk = 0.27. Determine how much work the applied force does in moving the box 2 m. Explain your solution.



I can figure for the force of friction = 35.986N. I cannot figure out how to find the net force without the applied force. Does the Friction force in this case = the net force?







Palarran or someone help!

Blah... I probably could have helped you when I was in school... I don't really remember any of my physics =X I did get an A though hehe.

Have a stupid physics exam tomorrow. Been going over a problem that I cannot figure out and it's bothering me.

3. A horizontal force pulls a 13.6 kg box across the floor at constant speed. The coefficient of kinetic friction between the box and the floor is mk = 0.27. Determine how much work the applied force does in moving the box 2 m. Explain your solution.

I can figure for the force of friction = 35.986N. I cannot figure out how to find the net force without the applied force. Does the Friction force in this case = the net force?

Palarran or someone help!
The force you calculated (~36N) is the force necessary to move the object across the surface with the frictional coefficient you noted (the applied force you were looking for). Thus, to move it 2m, you need to apply that force over that distance to get the work.

The constant speed noted in the problem statement tells you that you're not accelerating the object, therefore the only force being applied is that which overcomes the force of friction.

So, your answer would be ~72 N-m (or J).

Basic rule of physics panic:
Check your units.

It's amazing how easy it is to get force, acceleration, momentum, distance, velocity, time and all the rest confused.