Mathematics

Problem

The velocity of a body is expressed as

v(t)=4 t - t^{2}

(SI units). At what time is the acceleration zero, and what is the magnitude of the velocity at that instant? a)

t = 4\,\text{s},\; v = 4\,\text{m s}^{-1}

t = 2\,\text{s},\; v = 4\,\text{m s}^{-1}

t = 4\,\text{s},\; v = 0\,\text{m s}^{-1}

t = 2\,\text{s},\; v = 6\,\text{m s}^{-1}