Question

Kelly met Jesse and Liza at the max for breakfast. The graph shows Kelly’s speed during her 12 minute drive

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Answer:

D. $-360\,\frac{km}{h}$

Step-by-step explanation:

Physically speaking, average acceleration ($\bar a$), measured in kilometers per square hour, is defined by following formula:

$\bar a = \frac{v_{f}-v_{o}}{t_{f}-t_{o}}$ (1)

Where:

$v_{o}$, $v_{f}$ - Initial and final speed, measured in kilometers per hour.

$t_{o}$, $t_{f}$ - Initial and final instant, measured in hours.

The initial and final instants are, respectively:

$t_{o} = 5\,min\times \frac{1\,h}{60\,min}$

$t_{o} = 0.083\,h$

$t_{f} = 9\,min \times \frac{1\,h}{60\,min}$

$t_{f} = 0.15\,h$

If we know that $t_{o} = 0.083\,h$, $v_{o} = 60\,\frac{km}{h}$, $t_{f} = 0.15\,h$ and $v_{f} = 36\,\frac{km}{h}$, then the average acceleration of Kelly is:

$\bar a = \frac{36\,\frac{km}{h}-60\,\frac{km}{h}}{0.15\,h-0.083\,h}$

$\bar a = -358.209\,\frac{km}{h^{2}}$

The correct answer is D.