[maths] position function; calculus

  • From: "Ned Granic" <ngranic@xxxxxxx>
  • To: <maths@xxxxxxxxxxxxx>
  • Date: Tue, 5 Dec 2006 11:45:40 -0700

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

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