6.1 Accumulation + Net Change
- If R(t) is a rate, net change on [a,b] is ∫abR(t)dt. New amount = initial amount + net change.
- Area above the axis contributes positive change; below contributes negative change. Total change ≠ total amount.
- Units: (rate units)(input units). Example: gallons/min × min = gallons.
- On the interval [a, b]: displacement = ∫_a^b v(t) dt (net change in position, can be negative); total distance traveled = ∫_a^b |v(t)| dt (split the integral at times where v(t) = 0 to evaluate).
On a graph of a rate, use signed geometric area whenever possible.


