# Simple harmonic motion velocity and acceleration

## Homework Statement

An oscillator consists of a block attached to a spring (k = 125 N/m). At some time t, the position (measured from the system's equilibrium location), velocity, and acceleration of the block are x = 0.800 m, v = -11.3 m/s, and a = -119 m/s2

(a) calculate the frequency of oscillation (Hz)

(b) calculate mass of block (kg)

(c) calculate the amplitude of motion (m)

## Homework Equations

v(t) = -angular frequency(displacement)sin(phase)
a(t) = - angular frequency^2(displacement)cos(phase)
phase = angular frequency(t) + phase angle

## The Attempt at a Solution

-11.3 = -angular frequency (.8) sin (angular frequency x t + phase angle) but i have 3 variables

i feel like there is some simple and fairly easy way to do this... i just dont know what it is

thank you for the help

Alex

LowlyPion
Homework Helper
So isn't

a(t) = - ω2*x(t)

and since F = m*a = -k*x then substituting for a ...

ω2 = k/m

thank you very much that was quite helpful, but im having some problems with the amplitude calculation...

i found the equation K = Ma/A where A is amplitude but that just gives me the original displacement

125 = (.84 x -119)/ A

A = .8

any ideas?

Kurdt
Staff Emeritus
Gold Member
What will the acceleration and velocity be when the bob is at a maximum displacement?