Question

The position of a particle is described for the function x=2.3t^3 - 3.9t + 6.2(m). Determine the instantaneous acceleration (in m/s^2) for the time t=2.3s.
oobleck
v = dx/dt = 6.9t^2 - 3.9 m/s
a = dv/dt = 13.8t m/s^2
so now use your value for t.