# Required power.

joepro
Hello, I am having a hard time figuring out some physics problems.

The problem states.

How much power is required to pull a wagon weighingi 32200N at the speed of 25.0km/hr f the coefficient of rolling resistance is 0.200? What is the kinetic energy of the wagon?
______KW
______J

Thanks for the help!!!!

## Answers and Replies

Homework Helper
What equations do you think you will need to solve this problem?

joepro
I knowI need Ff=UN but otherwise I do not understand how to put the acceleration problem together with the friction problem or where to even start.

Homework Helper
I knowI need Ff=UN but otherwise I do not understand how to put the acceleration problem together with the friction problem or where to even start.

You don't need acceleration for this problem. You can get Ff using the formula. So now how does Power relate to force and velocity?

joepro
My U is .200 and I know that Ff=U * normal force. How do I find the normal force, then one I find the normal force what do I do to find the required power. I just need some steps and guidence. Thanks

Homework Helper
My U is .200 and I know that Ff=U * normal force. How do I find the normal force, then one I find the normal force what do I do to find the required power. I just need some steps and guidence. Thanks

The normal force or the normal reaction is an upward force acting on the car. The only other force acting in the vertical direction is the weight which acts downwards. So if the car does not move up or down, then what is the normal force equal to?