(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The force constant of a spring is 400 N/m and the unstretched length is .65 m. A 2.0 kg block is suspended from the spring. An external force slowly pulls the block down, until the spring has been stretched to a length of .78 m. The external force is then removed, and the block rises. In this situation, when the spring has contracted to a length of .66 m, the acceleration of the block, including direction is closest to:

(multiple choices given)

2. Relevant equations

I guess since it's a spring problem, the relevant equations would be potential energy=(1/2)kx^2 and maybe F=-kx.

3. The attempt at a solution

This problem is from a test I'm correcting so I know that the answer is 7.8 m/s^2 downward. However, I have no idea where to start. I considered that I would use (1/2)(400)(.78-.65)^2-(1/2)(400)(.66-.65)^2 to find the net work done, but I don't know where to go from there. I'm sorry my attempt at a solution is so minimal, but as I said before, I really don't know where to start. If this isn't sufficient enough please tell me.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Block on a spring problem

**Physics Forums | Science Articles, Homework Help, Discussion**