# Homework Help: Force and position problem?

1. Oct 10, 2011

### matt@USA

1. The problem statement, all variables and given/known data

The force shown in the figure acts on a 1.7kg- object whose initial speed is 0.44m/s and initial position is x=.27m. Find the speed of the object when it is at the location x=.99m. At what location would the object's speed be 0.32m/s ?

2. Relevant equations
I know that W=Fd. K=1/2mv^2. Vf^2=Vi^2+2ad.

3. The attempt at a solution
I have no clue where to start. I am completely lost. Where do, or how do I begin? Thanks for the help!
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

#### Attached Files:

• ###### Walker4e_ch07_Pr040.jpg
File size:
6.2 KB
Views:
277
2. Oct 10, 2011

### lightgrav

compute the initial KE, at its initial location.
That KE is changed by the F.d , as it moves along:
(.8N)(.23m) extra as it crosses the 0.5m mark. etc.

3. Oct 10, 2011

### matt@USA

Ok, so how does finding the Joules help me solve for velocity and location?

4. Oct 10, 2011

### lightgrav

the KE contains all the info to find out how fast it's going. (½mv.v)
it's about KE _at_ a location , just like it used to be "velocity at a time"

Notice that they ask "where was it going slower than at 0.27m?"