# Velocity and Position with Friction

1. Feb 13, 2015

### Westin

1. The problem statement, all variables and given/known data
A 27kg box is being pushed across the floor by a constant force [PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png96,0,0[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.pngN. [Broken] The coefficient of kinetic friction for the table and box is 0.14. At t=6s the box is at location [PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png7,6,7[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.pngm, [Broken] traveling with velocity [PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png9.5,0,0[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.pngm[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmmi10/alpha/144/char3D.pngs. [Broken]

What is its velocity at 8.6s?

What is its position at 8.6s? (Hint: Because the time step is so large, make sure to use the average velocity for this prediction.)

2. Relevant equations

Kinematic Equations
Position Update Equations
Friction Equations

3. The attempt at a solution
How I found velocity..
Force of friction = .14*27*9.8 = 37.044
acceleration = (96N - 37.044)/27 = 2.18m/s^2
Final Velocity = Vi + 2.18(2.6) = 15.1736m/s

Last edited by a moderator: May 7, 2017
2. Feb 13, 2015

### Staff: Mentor

I didn't check your numbers, but it looks like you made a good start. Now how can you find the second answer? What is the kinematic equation for position as a funtion of acceleration and time?

Last edited by a moderator: May 7, 2017