Homework Help: How far does each can slide on the table?

1. Nov 16, 2009

kashiark

1. The problem statement, all variables and given/known data
In a hardware store, paint cans, which weigh 46N each, are trasnported from storage to the back of the paint department by placing them on a 24 degree ramp. The cans slide down the ramp at a constant speed of 3.4 m/s onto a table made of the same material as the ramp. How far does each can slide on the table?

2. Relevant equations
mgsin(x) = component of gravity in the same dimension as the incline on which the object sits
KE = mv²/2
ΔKE = Fd

3. The attempt at a solution
46sin(24) ≈ 18.7
-(46/9.8)(3.4)²/2 = -18.7d
d ≈ 1.5
My problem is if the friction force were equivalent to the force of gravity down the incline, the the paint cans would never move.

2. Nov 16, 2009

Slip

Re: Energy?

The frictional force and the force propelling the cans down the incline must be equal, as the cans are moving at a constantly velocity, so all forces are in equilibrium.

I think we're assuming the cans are originally given some speed to begin with, and aren't placed on the ramp stationary, as the question does say it has a velocity.