Question 1006618
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The procedure is as follows:

1. Take the derivative of s by t.
   You will get a quadratic polynomial of t for the velocity, v(t) = {{{(ds)/(dt)}}}.

2. Solve the quadratic equation v(t) = -2 to find the time moment when the velocity is - 2 {{{m/s}}}.

3. Take the second derivative of s by t to get the expression for the acceleration a(t).

4. Substitute the found value of t into the expression for acceleration to determine the unknown acceleration.


Good luck!
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