Spring Problem

1. Dec 11, 2004

physicsss

A block of mass m is attached to a horizontal spring with constant k. resting on top of this block is another block of mass m. a coefficient of static friction mu exists between the two blocks. now suppose the spring is initially at equilibrium length, and someone gives it a push. the block moves in SHM in response. At a certain distance from equilibrium, the top block starts wo slide off the bottom one, find the x in terms of the given quantities and g.

So with the the moment when the top block slides off the block is when umg=ma? and where do I go from here?

2. Dec 11, 2004

futb0l

$$\mu mg = kx$$

The spring force = the frictional force.

3. Dec 11, 2004

Staff: Mentor

Right. So this tells you the maximum acceleration that the top block can withstand before it starts sliding. So find the acceleration of the system as a function of distance from the equilibrium postion. (You know the force on the system from the spring, and you know the mass of the system.)

4. Dec 11, 2004

Skomatth

Hey futb0l,

Are you sure about that? I could be wrong but for the top block $$ma <_= \mu m g$$ (couldn't figure out less than or equal sign) . So when it isn't slipping $$kx = 2ma$$