- #1

JJBladester

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## Homework Statement

A 4-lb collar which can slide on a frictionless vertical rod is acted upon by a force

**P**which varies in magnitude as shown. Knowing that the collar is initially at rest, determine its velocity at

*(a)*t = 2s

*(b)*t = 3s.

__Answers:__

*(a)*29.0 ft/s

*(b)*77.3 ft/s

## Homework Equations

[tex]mv_1+\sum Imp_{1\rightarrow 2}=mv_2[/tex]

## The Attempt at a Solution

[itex]mv_1+[/itex] Area under F vs. t graph [itex]=mv_2[/itex]

[tex]v_2=\frac{\left (\frac{1}{2} \right )(2)(10)}{\frac{4}{32.17}}=80.43ft/s[/tex]

I did not get the book's answer of 29.0 ft/s for part

*(a)*. Why?