View Full Version : Bar of soap
strugglin-physics
Oct3-04, 04:59 PM
A wet bar of soap slides freely down a ramp 9.35 m long inclined at 7.00°. How long does it take to reach the bottom? Assume muk = 0.0550.
Okay I've got my x & y componants
9.35cos(7)=9.28
9.35sin(7)=1.14
But now what since I don't have the mass of the soap or the acceleration, what do I do next?
Draw yourself a free-body diagram of the situation. It should be pretty clear to you from then on.
strugglin-physics
Oct3-04, 05:35 PM
Okay I drew my FBD but I still don't know how much time it would take the soap to slide down the ramp. Maybe I'm missing something.
I have the frictional force going NW the normal force going NE and the weight force going South... is that right?
Yes. Set up the equations using Newton's 2. law, solve for the acceleration and use some kinematics to solve for time.
strugglin-physics
Oct3-04, 06:27 PM
How do I solve for acceleration if the mass is unknown?
Well, but since the frictional force, the gravity and the "ma" terms are all proportional to the mass, it's a common factor which you can eliminate
(the solution is independent of the mass)
vBulletin® v3.8.7, Copyright ©2000-2012, vBulletin Solutions, Inc.