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?

 

[Moetasim]

I would first clarify the given information and make sure that the figure and the given equation are accurate and applicable to the problem. I would also ask for any additional information that may be needed to solve the problem accurately.

If the given equation is correct and applicable, then I would proceed with solving the problem by plugging in the given values. In this case, we have V(i) = 0 m/s, t = 4s, and the area under the curve can be calculated using the formula for the area of a trapezoid. Once I have the correct value for the area, I would then use the given equation to solve for V(f), which should give the correct velocity at t=4s.

It is also important to consider the units of the given values and make sure they are consistent. If the given values are in different units, then they should be converted to the same unit before plugging them into the equation.

In addition, I would also check if the given force is a net force or if there are other forces acting on the object. This could affect the velocity calculation and should be taken into consideration.

Lastly, I would double-check my calculations and make sure I have the correct sign for the velocity. If my solution still does not match the given answer, then I would carefully review my calculations and check for any mistakes.