Prove: a) that x = Asin wt is a solution of theequation of motion: m\dot \frac{d^{2}x}{dt^{2}}=-k\dot x of the harmonic oscillator. b) that w=\sqrt{k}

Cabiolab

Cabiolab

Answered question

2021-01-15

Show: a) that the motion equation's solution, x = asin wt:
md2x dt 2˙=kx˙ of the harmonic oscillator. 
b) that w=k{m} 
c) that the momentum is given by p = mwAcoswt 
d) the particle is stationary if and only if x = A 
(To get the time when x = A, use the formula x = A sinwt. Then, use this time in an expression for the velocity.) 
e) that the energy of a harmonic oscillator is 12kA2

Answer & Explanation

yagombyeR

yagombyeR

Skilled2021-01-16Added 92 answers

a). The net force is given by F=kx using Newton's second law F=m a where mis the mass and a is the acceleration
F=m a=k x acceleration (a) is second derivative ofx such that -k x = md2xdt2 solution to this differential equation is x=Acos(wt)=Asinwt
b). To prove w=k/m substitute the values x=Acos(wt+?) and d2xdt2=Aw2cos(wt) in kx=md2xdt2Akcos(wt)=Amw2cos(wt) divide both sides by - Acos(wt+)k=mw2w=km
c). momentum is given by p=mv where v=dxdtp=mwAcoswt
e). Energy of the harmonic oscillator total E=P.E+K.E
P.E=12kx2=12kA2cos2(wt)
K.E=12mv2=12m(dxdt)2=12mw2A2sin2(wt)
Total E=12kA2cos2wt+12mw2A2sin2wt=12kA2(cos2wt+sin2wt)=12kA2

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