- #1

- 43

- 0

http://img522.imageshack.us/img522/3064/physicsblockfx4.gif [Broken]

**A box slides across a frictionless floor with an initial speed v = 2.8 m/s. It encounters a rough region where the coefficient of friction is µk = 0.7.**

a) What is the shortest length of rough floor which will stop the box?

b) If instead the strip is only 0.28 m long, with what speed does the box leave the strip?a) What is the shortest length of rough floor which will stop the box?

b) If instead the strip is only 0.28 m long, with what speed does the box leave the strip?

**Relevant Equations:**

Work Energy Theorem, Chane in Kinetic Energy = Work done on box.Work Energy Theorem, Chane in Kinetic Energy = Work done on box.

**I already found the answer to part a.)**

(1/2)mv(final)^2 - (1/2)mv(initial)^2 = Ffriction

where i got: (1/2)(2.8)^2 = 0.7(9.81) * x

when i solved for x i got 0.571m

But its part b.) that i'm having the problem with. I set the problem up the same but solved for the velocity while i put in .28m for the distance(1/2)mv(final)^2 - (1/2)mv(initial)^2 = Ffriction

where i got: (1/2)(2.8)^2 = 0.7(9.81) * x

when i solved for x i got 0.571m

But its part b.) that i'm having the problem with. I set the problem up the same but solved for the velocity while i put in .28m for the distance

## Homework Statement

## Homework Equations

## The Attempt at a Solution

Last edited by a moderator: