Homework Help: Friction vs. Acceleration

1. Feb 8, 2009

Blueice781

1. The problem statement, all variables and given/known data
You are transporting a \$150,000 Dale Chihouly glass sculpture in your van. You stop at a hotel, where they have a valet parking. The valet gladly takes the wheel of your car and covers 20 meters from rest in 2.00 seconds. Between the sculpture and the floor of you van, mustatic=1.00 and mukinetic=.60, the sculpture is 3.00 meters from the back of the van.
a. Prove that the sculpture will start sliding towards the back of the van.
b. How long will it take the sculpture to accelerate from rest to slide 3.0 meters and smash into the back wall of the van?
c. How fast will the sculpture be going as it collides with the back of the van?

2. Relevant equations
2ax=v2-vo2
There might be more, but I don't know.

3. The attempt at a solution
a. 2a(20)=102-0
a=2.5m/s2

2. Feb 9, 2009

Kurdt

Staff Emeritus
Welcome to PF!

If you are given position and time and asked to work out acceleration you are better off using a different kinematic equation. I don't see the question telling me the final velocity is 10m/s anywhere. Once you have the acceleration of the van, compare the amount of force on the sculpture with the maximum static friction force.

3. Feb 9, 2009

miller8605

fnet = ma

you need to figure out your acceleration, then prove with a static equation that you have enough fnet to overcome mu static. Then use mu kinetic to determine the acceleration of the sculpture relative to the van. I don't remember the equations right off hand, but with a couple of equations it won't be too hard.