# Elastic Gravitational Potential ENergy

1. Jun 18, 2007

### salman213

1. A spring is suspended froma ceiling and a 256 g mass is attached to it and pulled down to stretch the spring by 18.2 cm. THe mass is released and travels through the equilibrium position with a speed of 0.746 m/s. Calculate the force constant of the spring/

2. 1/2kx^2 = Ee
1/2mv^2 = Ek
Eg = mgh

3. (DeltaEk - DeltaEg) = DeltaEe
I made my reference point where the spring is stretched until so i guess it has a heigh of 18.2 cm
1/2(0.256)(0.746)^2 - (0.256)(9.81)(0.182) = 1/2k(0.182^2)

and i solve for k

I have another post alread so if u have not read that what then ill tell u here that i have an exam comming up in a few days so i was reviewing my old review problems/tests/ and i found this question on my older test that i screwed up..but he never went through how to do it so i d k how to do it lol

thanks for anyones help in advance:)
This quest

2. Jun 18, 2007

### salman213

3. Jun 18, 2007

### Dick

You have the right concept but you want DeltaEe-DeltaEg=DeltaEk. Potential energy of spring-gravitational potential energy=kinetic energy.

4. Jun 18, 2007

### salman213

ahhh that makes sense cool..

so since the energy of the spring is being converted to kinetic energy but some of the spring energy is being reduced due to gravitational energy not all of it gets transfered to kinetic..right?
so basically

1/2(0.256)(0.746)^2 = 1/2k(0.182^2) - (0.256)(9.81)(0.182)

and hten i solve for k..

5. Jun 18, 2007

### Dick

Exactly correct.