# Mass spring system.

## Homework Statement

[/B]A simple harmonic oscillator consists of a block of mass 2.00 kg attached to a spring of spring constant 100 N/m.When t =1.00 s, the position and velocity of the block are x =0.129 m and v =3.415 m/s. (a) What is the amplitude of the oscillations? What were the (b) position and (c) velocity of the block at t 0 s?

## Homework Equations

x(t)=X*cos(ωt+Φ)
v(t)=-ω*X*sin(ωt+Φ)
ω=sqrt(k/M)

## The Attempt at a Solution

so finding the angular velocity was easy. Just plugging in the values for k and m yielded 7.07rad/s
i lost on where to go next. I think my understanding of the phase and Φ is a little weak. I was to just use the equation for displace meant and velocity, make Φ zero and plug in the other values, but I am prety sure that is wrong.

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gneill
Mentor
For (a) you might want to consider an energy approach. Note what happens if you divide v by x (using the formulas that you provided).
The amplitude cancels and you are left with only one unknown (phi).
Then the rest of the problem should be straightforward.