Calculating Motion on a Ramp Without Mass

[BraedenP]

Homework Statement

A train is traveling up a 5.0 degree incline at a speed of 2.55 m/s when the last car breaks free and begins to coast without friction. How long does it coast before stopping momentarily?

Homework Equations

$$F=mg$$ or $$F=ma$$ more generally.

The Attempt at a Solution

I would normally use the object's mass to find a vertical force of gravity, and then use the degree of incline to find the force directed down the ramp, with which I could calculate acceleration and solve for the time.

However, without a given mass, I'm stuck..

How do I find a force (or is there a straight way to get the acceleration?)

 

[thrill3rnit3]

1. F(net) does not equal mg in this situation.
2. Draw your sum of forces, and work out the algebra. Mass eventually cancels out.

 

[BraedenP]

1. F(net) does not equal mg in this situation.
2. Draw your sum of forces, and work out the algebra. Mass eventually cancels out.

Oh duh! I'm so retarded sometimes.. All I needed to do was work out the component of gravitational acceleration pointing down the ramp. No force calculations required at all.

Thanks! :P