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cutie314
Feb25-05, 12:07 AM
A 2.4-kg block is dropped onto a spring of spring constant 3955 N/m from a height of 5.0 m. When the block is momentarily at rest, the spring has been compressed by 25 cm. Find the speed of the block when the compression of the spring is 15 cm.

Because energy is conserved, shouldn't mgh=1/2kx^2? but (2.4)(9.81)(5)=117.72. and 1/2(3955)(.25)^2=123.59375. Where did I go wrong?

learningphysics
Feb25-05, 01:19 AM
A 2.4-kg block is dropped onto a spring of spring constant 3955 N/m from a height of 5.0 m. When the block is momentarily at rest, the spring has been compressed by 25 cm. Find the speed of the block when the compression of the spring is 15 cm.

Because energy is conserved, shouldn't mgh=1/2kx^2? but (2.4)(9.81)(5)=117.72. and 1/2(3955)(.25)^2=123.59375. Where did I go wrong?

You should post this in the homework section.