# Mass on spring

1. May 13, 2010

### bon

1. The problem statement, all variables and given/known data

Mass m attached to spring with spring constant k=Am. It feels a resistive force magnitude Bmv where v is the speed. and A, B are constants such that 4A > B^2

What is the fractional change in amplitude of oscillation in one complete oscillation?

2. Relevant equations

3. The attempt at a solution

Ok so ive written down the DE:

x'' + Bx' - Ax = 0 and solved..but this gives be Ce^-Lt + De^-L't where C, D, L and L' are constants...

1) i dont see how this oscillates... 2) how do i work out fractional change in amplitude of oscillation?

2. May 13, 2010

### tiny-tim

Hi bon!

(try using the X2 tag just above the Reply box )
Nooo

3. May 13, 2010

### bon

Why not? I thought this was a direct consequence on NII (and cancelling the m)

4. May 13, 2010

### tiny-tim

One of the signs is wrong.

5. May 13, 2010

### bon

ok i see thanks i can now solve the eqn but how do i find fractional change in amplitude of oscillation

6. May 13, 2010