A particle has v = t³ − 6t² + 9t + 4. Find its average acceleration between the two instants at which instantaneous acceleration is zero.

Question

G1 Physics · Accepted Answer

a = dv/dt = 3(t−1)(t−3). Hence a=0 at t=1 s and t=3 s. v(1)=1−6+9+4=8 m s⁻¹. v(3)=27−54+27+4=4 m s⁻¹. Average acceleration = [v(3)−v(1)]/(3−1) = (4−8)/2 = −2 m s⁻².