Solved it! Nope. -- Piano slipping down a ramp 1. The problem statement, all variables and given/known data Two men loading a 900 kg piano onto a truck lose control and the piano slips, rolling down the loading ramp. The ramp is a 12 degree incline that is 3.2 m long. How long does it take the piano to reach the bottom of the ramp? Assume there is no friction. 2. Relevant equations My physics teacher found this equation for acceleration for an object on an incline: a=g(sin)(theta)-(mu)g(cos)(theta) I tried tweaking it a bit. I think the (mu)g(cos) can be left out since mu is zero. a=g(sin)theta a=9.8(.20) a=2.03 m/s^2 Easy, right? 3. The attempt at a solution Nope. Not easy. The equation I found above doesn't take mass into consideration. Using this acceleration as my change in velocity, I get t=2.03/3.2=0.63 s. Reasonable enough. But what about the mass? Where did I go wrong? Thanks in advance!