# Compression of spring wrt speed

brunettegurl

## Homework Statement

A block sliding along a horizontal frictionless surface with speed v collides with a spring and compresses it by 2.34 cm. What will be the compression if the same block collides with the spring at a speed of 4.00v?

## Homework Equations

e=0.5mvSUP]2[/SUP] e= 0.5k*x2

## The Attempt at a Solution

i thought abt equating the two and solving it in regards but there are too many unknown values to cancel them out...and also to find a way to make a connection btw the given information.
my next thought was to times the given compression by 4 since the speed is also increased but that proved to be wrong..pls. help

Mentor
my next thought was to times the given compression by 4 since the speed is also increased but that proved to be wrong
That should be correct. [edit: At first I said it was wrong, but I didn't read it carefully.]

Set up a ratio to verify it.

Last edited:
Gold Member
Equate both energies, potential and kinetic for both systems independently. Then divide the equations against each other and see what pops out.

brunettegurl
ok ...so I'm a little confused abt the divide them against part..so if i do that the k and m would cancel off living (v2+16v2)= (0.0234)2(x2)...does that look right or am i totally off track??

Mentor
ok ...so I'm a little confused abt the divide them against part..so if i do that the k and m would cancel off living (v2+16v2)= (0.0234)2(x2)...does that look right or am i totally off track??
I don't quite understand what you did. Yes, the m and k drop out, but you should have v12/v22 = x12/x22 (or equivalent).

(Read my correction to my last post.)

brunettegurl
ok thanks