# Physics help Plz

1. Nov 4, 2004

### bballgirlweez

The most massive car ever built was the official car of the general secretary of the communist Party in the former soviet union. suppose this car is moving down a 10 degree slope when the driver suddenly applies the brakes. The net force action on the car as it stops is -2.00 x 10^4 N. If the coefficient of kinetic friction between the car's tires and the pavement is .797, what is the car's mass? what is the magnitude of the normal force that the pavement exerts on the car?

I've tried these problems many times I would just need an equation and I can do the math it's just the applying that gets me switching around stuff to get different answers I can do but I really need help on this

There were questions on the test like this today and I had to guess cuz I wasn't sure how to do them correctly

Last edited: Nov 4, 2004
2. Nov 5, 2004

### Chi Meson

Could you check this question? There should be either "how much time" or "how far" the force is applied to stop the car. You can not get the mass of the car without one of those quantities.

Edit: NO, NO, my bad, I see the car is skidding to a stop.

The two forces that are parallel to the plane are "the parallel componant of the weight" which points down the incline, and the frictional force which points up the incline. The difference between these two forces is the net force (given).

After you find the mass, the normal force will be equal to the "perpendicular componant of the weight."

Do you recognize any of these?

Last edited: Nov 5, 2004