How can I calculate maximum velocity in simple harmonic motion?

I know that the equation for velocity is

V=ωAsin(ωt+ϕ)

supposing ϕ to be zero , cuz if the object is released from the mean position then, at the mean position displacement is zero so,

sinϕ = 0 →ϕ = 0.

I know from the velocity time graph for SHM that max velocity = Aω.

That is the argument must be -1

How will that be possible ? the argument can only be zero for 2π3 right?

Am I missing something?

1 Answer
Dec 26, 2017

Please see the following explanations.

Explanation:

enter image source here

  • we recommend that you first watch the animation carefully

  • Let P be a point rotating around the O point at a constant linear velocity(u).

  • The projection of P on the x-axis is point B.

  • The movement of point B is limited between A and F.

  • The simple harmonic motion is the action of point B.

  • Please note that the velocity vector changes direction.

  • At points A and F, the velocity of B is zero(green vector).

  • The greatest velocity B has is at O.θ=π2andθ=3π2

x=rcosθ

θ=ω.t

x=r.cos(ωt)

dxdt=v

dxdt=v=rωsinωt

if ωt=π2 or ωt=3π2 , v=rω(maximum velocity)

vmax=rω

or :

y=rsinθ

dxdt=v=ωy

x2+y2=r2

y=r2x2

v=ωr2x2

if x=0 v=vmax