# Urgent: Spring Compression Problem

reklaws89

## Homework Statement

Use work and energy to solve the following. A .1 kg ball is placed against a massless spring that has a stretch constant 50,000 N/m and is compressed 2 m. The spring fires the ball straight up. a) How far did the ball rise assuming no friction? b) The ball's actual rise was 2m short of the answer in part A. What was the frictional work done by air?

1/2ky^2=mg(h+y)

## The Attempt at a Solution

I figured out part A to be 102,038 m... which seems outrageous, but the numbers in this problem are also outrageous. I'm really just struggling on how to do B or even attempt it.

Homework Helper
Gold Member
You need to show some work to get help here. How did you end up with your answer in part a?

reklaws89
I used the equation (KE + PEg + PEs)i = (KE + PEg + PEs)f

KEi=0
KEf=0
PEgi=0
PEsf=0

PEsi=1/2ky^2
(y=compression)
PEgf=mg(h+y)
(h=distance traveled)

therefore, 1/2ky^2=mg(h+y)
so 1/2(50,000N/m)(4m)^2=.1kg(9.8m/s^2)(h+2m)
100,000Nm=.98N(h+2m)
102,040m=h+2m
102,038m=h