 #1
Zero
 17
 4
 Homework Statement:

Problem: A spring is compressed 50 cm from the equilibrium position. The spring constant is 12 N/cm. A 20 kg object is placed next to the spring initially at rest and it is released. After the object is released from the spring, the force of friction acting on the object is 30 N.
A) Calculate the force required to compress the spring by 50 cm. (Already got the answer which is 600N)
B) Calculate the energy that was stored in the spring. (Got this answer also which is 150 J)
C. Calculate the object's velocity 4m after it has left the spring. (This is where I stopped don't know what to do here)
What I tried: Unfortunately I don't know where to begin. I know what variables are which are work, spring constant, friction and potential energy in the spring which is the same as the work.
As for number 3, I'm totally lost but I do have a theory that I don't know if it would be true for this specific equation.
Theory: Would I have to find kinetic energy first.
The reason that I have such a theory is because of question D which I did not add since I did not attempt it as of yet but as of posting this, I will be attempting.
 Relevant Equations:
 F=Kx and W=1/2FX
Et1+w=Et2
1/2mv+w=1/2mv
0+150=1/2 (20)
300=(20)v
15=v
I know this answer is wrong.
1/2mv+w=1/2mv
0+150=1/2 (20)
300=(20)v
15=v
I know this answer is wrong.