HELP!

A block slides down a straight ramp at 45 degrees in two trials:
1) the ramp is not secured to the ground and there is no friction between the block and the ramp.
2) the ramp is secured to the ground and there is still no friction between the block and the ramp.

Explain in which trial the block will have more speed and why.

Question

HELP!

A block slides down a straight ramp at 45 degrees in two trials:
1) the ramp is not secured to the ground and there is no friction between the block and the ramp.
2) the ramp is secured to the ground and there is still no friction between the block and the ramp.

Explain in which trial the block will have more speed and why.

caominhim · Answer

The answer is the unattached ramp.

I know this because I remember getting this question on a test in high school.  The following explanation might be wrong so don't quote me.

When the block slides down the ramp it is accelerated by a component of gravity.  When the ramp is unattached a component of the normal force at the base counteracts the friction force.  Then for whatever reason this increases the component accelerating the box down the ramp.