# Inclined plane acceleration

leonidas24
Consider the classical physics problem of a cube sitting atop a frictionless inclined plane. Of course, this cube will accelerate down the plane with acceleration dictated by F = mgsin(theta), where theta is the angle between the inclined plane and the horizontal surface.

Easy enough.

Now, my question is this; if the inclined plane was itself sitting atop a frictionless, horizontal plane, would it too accelerate in some direction as the cube slides down its surface? In order to conserve momentum, for instance?

Gold Member
Just write out the force equation and that should do it. Have faith, my lad! Physics works.

Gold Member
The cube would have a simple vertical free fall and the inclined plane would move out of its way as the cube goes down since it doesn't have any restriction.

Mentor
Now, my question is this; if the inclined plane was itself sitting atop a frictionless, horizontal plane, would it too accelerate in some direction as the cube slides down its surface? In order to conserve momentum, for instance?
Of course.

The cube would have a simple vertical free fall and the inclined plane would move out of its way as the cube goes down since it doesn't have any restriction.
The cube is not in free fall. The incline exerts a force on it.