### Home > APCALC > Chapter 7 > Lesson 7.1.2 > Problem7-19

7-19.

A point travels along the $x$-axis so that at time $t$ its position is given by $s(t) = t^3 - 5t^2 + 4t$, where $0 ≤ t ≤ 5$.

1. ​What does $s(t)$ represent?

The point's position along the $x$-axis.

2. Where is the particle located when $t = 5$?

Calculate $s(5)$.

3. What is the velocity of the particle when its acceleration is zero?

Velocity is the derivative of position, and acceleration is the derivative of velocity.