Question

The position of a particle on a straight line is given by s(t) = 3 – cos(t).

Answer 1

Given the position function

s(t) = 3 - cos(t )

differentiate once to get the velocity, and twice to get the acceleration:

v(t) = s'(t) = sin(t )   →   v (4.3 s) ≈ -0.92

a(t) = s''(t) = v'(t) = cos(t )   →   a (4.3 s) ≈ -0.40

The acceleration is negative, so the particle is slowing down.