# Potential Elastic Energy

Can anyone help me with this question?

A 0.240 kg block on a vertical spring with a spring constant of 5e3 N/m is pushed downward, compressing the spring 0.080 m. When released, the block leaves the spring and travels upward vertically. How high does it rise above the point of release?

I know that PE= 1/2 kx^2
so I got .5 x 5e3 x .08^2=16 I'm not sure where the mass comes into this equation. I also know that you have to subtract your anser from the point of release so i tried 16-.08 but it didn't work...

Thank-you

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Is the answer you got (16) a height? What units does it have? What units should it have?

Secondly, if it reaches a maximum height while initially traveling upwards, then something must be pulling it down... what is it? (kinda obvious).

16 joules is the potential energy
where would you incorporate gravity or weight into the equation??

Doc Al
Mentor
Think of this as a conservation of energy problem. Intially, you have spring potential energy, which ends up being transformed into gravitational potential energy. How do you express gravitational PE as a function of height?

kp
doesn't the block have P.E. as it travels upto to its max height; how would you define the P.E of an object at a certain height?