AL PHY Qu. (about S.H.M)

2010-03-05 6:56 am

Qu:

An object performs simply harmonic motion. Which of the following physical quantities is doubled when its amplitude is double?

A. Period of oscillation

B. Maxium momentum

C. Maxium potential energy

D. Total mechanical energy

Ans : B

Please explain~ Thank you so much!

回答 (1)

Prof. Physics

2010-03-05 7:20 am

✔ 最佳答案

The answer is B.

For A, for S.H.M., the motion is isochronous. That is, the period of oscillation is independent of amplitude.

To choose between B, C and D, we first need to know the displacement, x = Asinwt

Velocity, x' = wAcoswt

Acceleration, x" = -w^2Asinwt

For B, momentum = mx' = mwAcoswt

So, when Amplitude A is doubled, momentum is also doubled.

For C and D, maximum potential energy = total mechanical energy = 1/2 mw^2A^2

So, when A is doubled, this value is four times larger.

參考: Physics king

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