Register to reply

Net work problem with F cos theta

by loganblacke
Tags: theta, work
Share this thread:
loganblacke
#1
Oct29-10, 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 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.


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!
Phys.Org News Partner Science news on Phys.org
Security CTO to detail Android Fake ID flaw at Black Hat
Huge waves measured for first time in Arctic Ocean
Mysterious molecules in space
paragchitnis
#2
Oct29-10, 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
paragchitnis
#3
Oct29-10, 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
vf2 = vi2 + 2ax

loganblacke
#4
Oct29-10, 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!!!
paragchitnis
#5
Oct30-10, 09:51 AM
P: 25
Thank you for giving new problem to me.
Is the answer correct?


Register to reply

Related Discussions
Proving: limit (as theta approaches zero) of sin(theta)/(theta) = 1 Calculus & Beyond Homework 2
Inequality involving theta and sin(theta) Calculus & Beyond Homework 1
Theta problem o_0 Introductory Physics Homework 13
Understanding Cosine Theta in Work Equation Introductory Physics Homework 2
Easy: given theta, uncertainity on cos(theta) Introductory Physics Homework 5