Calculating Velocity of a 2.0kg Object Subjected to Time-Varying Force at t=4s

[Baaadshah87]

urgent !Question about Dynamics

Homework Statement

A 2.0kg object initially at rest at the origin is subjected to the time-varying force shown in the figure .
What is the object's velocity at t= 4s

Homework Equations

The Attempt at a Solution

I used the equation V(f) = V(i) + area under the curve from 0s to t
My solution was -6m/s I got that wrong.

 

[G01]

First things first, you are using the wrong graph when you are finding the area under the curve. You want the area under the acceleration vs. time graph, not the force vs. time graph.

Also, think about your answer. It should not be negative. Can you tell me why?HINT: How can you relate acceleration to force? If you are able to answer this, can you use this relation to get an acceleration vs. time graph from the force vs. time graph?