
Qi L. answered 02/13/21
PhD in Physics from a top US University
v(t) = -t^2 + 4
0<=t < 2, v(t) > 0, particel travels in positive direction
at t = 2, v(t) = 0
t > 2, v(t) < 0, particel travels in negative direction
distance = distance traveled in positive direction + negative direction
r1 = ∫02 v(t) dt = 16/3
r2 = ∫24 v(t) dt = -32/3
d = |r1| + |r2| = 48/3 = 16