
#1
Oct2910, 10:41 AM

P: 48

1. The problem statement, all variables and given/known data
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 yaxis and s (meters) as the xaxis. 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. 2. Relevant equations Work=Force*Distance*cos(theta) 3. The attempt at a solution I don't understand what the y value represents or what values to assign for theta. Please help! 



#2
Oct2910, 11:01 AM

P: 25

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



#3
Oct2910, 11:16 AM

P: 25

Fcos[tex]\Theta[/tex] 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 vf^{2} = vi^{2} + 2ax 



#4
Oct2910, 12:36 PM

P: 48

Net work problem with F cos theta
A=.25/5.0=.05 m/s
Vf=sqrt(2*.05*8)=.8944 m/s^2 Thank you for your help!!! 



#5
Oct3010, 09:51 AM

P: 25

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


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