Mathematics

Problem

An object moves along a straight line. Its velocity-time graph is a parabola opening upwards with its vertex at

(t = 2\,\text{s}, v = -4\,\text{m/s})

. The object crosses the time axis at

t = 0\,\text{s}

and

t = 4\,\text{s}

. Identify the time interval during which the object is speeding up.