If the displacement of an object is given in SI units by Dx = -3 t + 4 t²,at t = 2 s its velocity and acceleration are,respectively: A)positive,positive. B)positive,negative. C)negative,negative. D)negative,positive.

Question

Quizplus · Accepted Answer

The velocity is the first derivative of displacement with respect to time: v = d(Dx)/dt = -3 + 8t. At t = 2 s, v = -3 + 8(2) = 13, which is positive. The acceleration is the derivative of velocity with respect to time: a = d(v)/dt = 8, which is positive.

If the Displacement of an Object Is Given in SI