How High Was the Plunger Released to Compress the Springs?

[JoshuaR]

1. An 8-kg plunger is released from rest in the position shown and is stopped by the two nested springs; the constant of the outer spring is k1 = 3kN/m and the constant of the inner spring is k2 = 1-kN/m. If the maximum deflection of the outer spring is observed to be 150mm, determine the height h from which the plunger was released.
Given a diagram. h is the height above the tallest spring, the outer spring. The outer spring is 90 mm higher than the inner spring.



2. mgh=PE .5kx^2=PE spring



3. mg(h+.15m) = .5k1(.15m^2) + .5k2(.06m^2)
Yielding an h of 0.509m.
Can someone inform me if this is the right path? It seems too simple...

 

[denverdoc]

there's a typo in your spring constant so can't confirm answer but work looks fine.

 

[JoshuaR]

sorry, k1=3kN/m and k2=10kN/m if I remember correctly. Thanks for the confirmation.