1. **State the problem:** We need to calculate the total distance travelled by the graphic from time $t=0$ to $t=15$ seconds.
2. **Understand the velocity function:** The velocity is given by $v(t) = t^2 - 14t + 40$. The graphic is at rest when $v(t) = 0$.
3. **Find when the graphic is at rest:** Solve $v(t) = 0$:
$$t^2 - 14t + 40 = 0$$
Factorizing:
$$(t - 4)(t - 10) = 0$$
So, $t = 4$ or $t = 10$ seconds.
4. **Calculate position values:** Given positions at these times:
- $x(0) = 0$
- $x(4) = 69 \frac{1}{3} = \frac{208}{3}$
- $x(10) = 33 \frac{1}{3} = \frac{100}{3}$
- $x(15) = 150$
5. **Calculate total distance travelled:** Total distance is the sum of absolute changes in position between these times:
$$d = |x(4) - x(0)| + |x(10) - x(4)| + |x(15) - x(10)|$$
Substitute values:
$$= \left|\frac{208}{3} - 0\right| + \left|\frac{100}{3} - \frac{208}{3}\right| + |150 - \frac{100}{3}|$$
Calculate each term:
$$= \frac{208}{3} + \frac{108}{3} + \left|150 - 33 \frac{1}{3}\right|$$
$$= 69 \frac{1}{3} + 36 + 116 \frac{2}{3}$$
6. **Sum the distances:**
$$d = 69 \frac{1}{3} + 36 + 116 \frac{2}{3} = 222$$
**Final answer:** The total distance travelled by the graphic is $222$ cm.
This method correctly finds the times when the graphic stops (velocity zero), then sums the absolute position changes between these times to get total distance, not just displacement.
Total Distance
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