Posted by Carden on Tuesday, March 30, 2010 at 9:53pm.
A 2.1 kg block slides with a speed of 1.1 m/s on a frictionless, horizontal surface until it encounters a spring.
(a) If the block compresses the spring 5.7 cm before coming to rest, what is the force constant of the spring?
(b) What initial speed should the block have to compress the spring by 1.8 cm?
I know that 1/2kx2 comes into play somewhere. I'm not sure hoe the velocity plays a role in all of this. I'm overall just completely confused.

Physics  Kelly, Wednesday, March 31, 2010 at 8:38am
A) ( 1/2 )kx^2 = ( 1/2 )mv^2
so.. k=mv^2/x^2
(make sure you convert 5.7cm to meters first.)
B) ( 1/2 )kx^2=(1/2)mv^2
so... v^2=kx^2/m
solve for v.