# Vertical spring physics

An 5 kg block is fastened to the top of a vertical spring (perpendicular to the floor) with a spring constant of 1000 N/m. A 3 kg block sits on top of the 5 kg block.

The springs are pushed down so that they oscillate.

I need help finding the magnitude of the maximum acceleration the blocks can obtain while still remaining in contact. I have no idea where to begin.

Related Introductory Physics Homework Help News on Phys.org
Hootenanny
Staff Emeritus
Gold Member
HINT: Consider the forces acting on the 3kg block, which force will be zero when the blocks lose contact?

Ok so when the blocks lose contact, the force of the spring-mass will be equal to the force of gravity on the 3 kg block.

M(3)*a=-2mg, is this correct?

Hootenanny
Staff Emeritus
Gold Member
You've still not answered my first question. What are the forces acting on the top block?

Last edited:
The forces acting on the block are gravity and the force of the spring, correct? Or friction??

Hootenanny
Staff Emeritus
Gold Member
The forces acting on the block are gravity and the force of the spring, correct?
Correct, but what I was trying to get at is that the force of the spring acts through the normal force exerted on the block. Hence, the net force acting on the block is $N - mg$. Can you now use this information to write an equation using Newton's second law?

ma = N - mg

but what is the magnitude of the normal force !?!?!? kx !?

Hootenanny
Staff Emeritus