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## Homework Statement

Object A (1 kg) and B (3 kg) are forced together,

initially compressing a spring S between them by 6 cm;

then the system is released from rest. The spring with

k=1250 N/m is not fastened to either block and drops to

the surface after it has expanded to its unstretched position.

a) By assuming frictionless surface, what are the speeds of objects after the spring has expanded

to its unstretched position?

b) Assume that the surface is frictional with s=k=0.1. If object B has speed of 0.2 m/s at 0.5 s

after the system is released from rest, what should the speed of object A be at this time instant?

(Hint: Consider “center of mass of a system” concep

## Homework Equations

W=1/2kx^2

F=k.x

K=1/2mV^2

## The Attempt at a Solution

i'm having trouble with this energy thing. i tried 1/2kx^2=1/2mv1^2+1/2mv2^2

i found 37,5=1/2v1^2 + 1/2v2^2

and i tried F=k.x=75 .

then used f=m.a formula both objects and found V1=3V2. so i solved equation but it seems all wrong.

can you help?