# Help with formulas for work & energy problems

1. Nov 15, 2009

### kingperfect

I was looking for help on figuring out the formulas for these questions on work and energy. Not looking for the answers, just the formula to solves these types of problems.

1. A box sits upon the floor. The box has a mass of 100. Kg. The coefficient of static friction between the box and the floor is 0.89. What is the maximum force that can be applied to the box without it moving?

3. A crate on a floor has an applied force (15 degrees below horizontal) of 050 N. The crate moves with constant velocity. The coefficient of kinetic friction is 0.15. What is the mass of the crate?

4. A car on a roller coaster has a mass of 0509 kg. The car is dragged up the main hill at an angle of 38 degrees (above horizontal) for a total distance of 190 meters to the top of the first hill. What work is done to the car?

6. Two people push on a crate. Person 1 pushes in the positive X direction with a force of 25 N. The second person pushed in the negative x direction, at an angle 15 degrees below the horizontal with a magnitude of 18.5 N. The box moves with uniform velocity. What is the force of friction between the box and the floor?

2. Nov 15, 2009

### rl.bhat

Hi kingperfec, welcome to PF.
When the box is moving on a floor, what are the forces acting on the box?

3. Nov 16, 2009

### kingperfect

other than the forces mentioned in the problems, there is no additional forces (ie wind, etc)

4. Nov 16, 2009

### Staff: Mentor

Welcome to the PF. I'm surprised that your textbook isn't being helpful with the equations you need. This wikipedia page should get you started:

http://en.wikipedia.org/wiki/Free_body_diagram

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