How Do You Calculate the X-Component of Force from Potential Energy?

[sracks]

A particle has the potential energy shown in the figure. See link below. What is the x-component of the force on the particle at x =5, 15, 25, and 35 cm?

All answers are in N

http://img111.imageshack.us/img111/4988/figure2vn4.jpg

i know i should be using -dU/dx
but i keep getting the wrong answers when x = 5 cm
I get F = 1N

 

[Doc Al]

Did you take into account the fact that the x-axis is marked in cm?

 

[sracks]

oh, thank you

 

[sracks]

I'm actually having trouble when x = 25 cm. Is there any advice on how to figure it out?

 

[mysqlpress]

I'm actually having trouble when x = 25 cm. Is there any advice on how to figure it out?

-dU/dx means the slope of U-r graph
slope of U-r graph between 20cm-40cm are the same.

 

[Doc Al]

I'm actually having trouble when x = 25 cm. Is there any advice on how to figure it out?

Use the same method used at x = 5 cm.