[maths] Re: position function; calculus

  • From: "Nelson Blachman" <blachman@xxxxxxx>
  • To: <maths@xxxxxxxxxxxxx>
  • Date: Thu, 07 Dec 2006 00:48:43 -0800

Ned,

  Your integrations are correct, but your substitutions of the values at time 
t=0 are wrong.

  While sin 0 = 0, cos 0 is not 0.

  HTH
  --Nelson
  ----- Original Message ----- 
  From: Ned Granic 
  To: maths@xxxxxxxxxxxxx 
  Sent: Tuesday, December 05, 2006 10:45 AM
  Subject: [maths] position function; calculus


  Hi all,

  Here is one little confusing question that needs some clarification.

  A particle is moving with the given data.
  Find the position of the particle.

  a(t) = cos t + sin t -- acceleration
  s(0) = 0 -- position at 0 seconds
  v(0) = 5 -- initial velocity.
  a(t) = v^'(t)  -- acceleration is a derivative of a velocity
  = cos t + sin t, that is, velocity is antiderivative of the acceleration, 
therefore, the velocity function is:
  v(t) = sin t-cos t+C
  which means that:
  5 = 0+C, that is:
  C = 5, and the required velocity function is:
  v(t) = sin t-cos t+5.
  Then, the velocity function is a derivative of the position function:
  v(t) = s^'(t), that is, the position function is antiderivative of the 
velocity function:
  s(t) = -cos t-sin t+5t+D, that is:
  0 = 0+D, or:
  D = 0, so the required position function here is:
  s(t) = -cos t-sin t+5t.

  The question is, what is the position of the particle with the given data?

  Many thanks in advance!
  Ned

Other related posts: