1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Simple Harmonic Motion question.

  1. Dec 25, 2011 #1
    1. The problem statement, all variables and given/known data

    We say that the equation a= ω2x defines simple harmonic motion - it tells us what is required if a body is to perform s.h.m. The equation x= xosinωt is then described as a solution to the equation, since it tells us how the displacement of the body varies with time. If you have studied calculus you may be able to differentiate the equation for x twice with respect to time to obtain an equation for acceleration and thereby show that the defining equation a = -ω2x is satisfied.

    2. The attempt at a solution

    I haven't done calculus as I haven't taken Math as a subject. I wanted to ask if it would be possible to understand that statement without taking calculus. Or if someone could explain to me what the whole point of the statement is. I really don't get it at all. Do tell me if I have to study a bit of calculus to understand this, because I will if I have to. Thanks :)
  2. jcsd
  3. Dec 26, 2011 #2
    Doing physics without taking calculus seems to be somewhat like welding without your hands (though this depends on what level of physics you're doing), if you plan on going very far calculus is a must though.
    The paragraph is saying that an object going in simple harmonic motion has an acceleration given by [itex] a = \omega ^2 x [/itex] and that if you do some calculus you can see that the equation of the position of that object is given by [itex] x = x_0 \sin \omega t [/itex].
    The actual calculus involved (differentiation) allows you to take the function of position and use that to find the velocity then use that to find the acceleration, and if you use the x function given to you then they're just telling you that it all works out nicely :)
    The take home points are really just that objects in SHM move according to [itex] x = x_0 \sin \omega t [/itex] and have an acceleration at a position x given by [itex] a = \omega ^2 x [/itex].
  4. Dec 26, 2011 #3
    Thanks a LOT for that! Seriously :)

    I'm doing A-Level/12th Grade physics [which the syllabus says DOES require a little bit of math i.e. differentiation, integration and the know-how of logarithms] but I don't take mathematics as a subject because I'm aiming to get into med school, plus I absolutely hate math so I didn't pursue it further. But I understood what you said.

    Just as a precautionary measure though, I'll learn differentiation and then come back to this statement again. Bet I'll understand it even better then. Thanks again!
  5. Dec 26, 2011 #4


    User Avatar
    Homework Helper

    It is not true: a minus sign is missing.
    a=-ω2x is valid for the simple harmonic motion.

  6. Dec 26, 2011 #5

    Yeah yeah sorry, typo. Thanks for correcting it.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook