How Is the Mass of a Block Determined When It Compresses a Spring?

[dorian_stokes]

Homework Statement

A block is dropped onto a spring with k = 31 N/m. The block has a speed of 3.5 m/s just before it strikes the spring. If the spring compresses an amount 0.11 m before bringing the block to rest, what is the mass of the block?

Homework Equations

0.5mv^2=0.5kx^2

The Attempt at a Solution

0.5m3.5=0.5*31*.11

 

[Delphi51]

Looks like you forgot to square the 3.5 and the .11.