Net work problem with F cos theta

[loganblacke]

Homework Statement

The graph below shows the component (Fcos(theta)) of the net force that acts on a 5.0 kg block as it moves along a flat horizontal surface. Find (a) the net work done on the block and (b) the final speed of the block if it starts from rest at s = 0.

The graph shows Fcos(theta)(N) as the y-axis and s (meters) as the x-axis. The coordinates are (0,0), (1,0), (1,2), (4,2), (4,-2), (6,-2), (6,0), (8,0), connected by straight lines in that order.

Homework Equations

Work=Force*Distance*cos(theta)

The Attempt at a Solution

I don't understand what the y value represents or what values to assign for theta. Please help!

 

[paragchitnis]

Work = Force x cos\Theta x distance
This is the area under the given graph between Fcos\Theta and s

 

[paragchitnis]

Fcos\Theta is the force acting in the direction of the motion of the body.
The acceleration of the body in the direction of motion can be calculated as
Force = mass x acceleration
After finding acceleration use
vf² = vi² + 2ax

 

[loganblacke]

A=.25/5.0=.05 m/s

Vf=sqrt(2*.05*8)=.8944 m/s^2

Thank you for your help!

 

[paragchitnis]

Thank you for giving new problem to me.
Is the answer correct?