Question

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

Answer 1

Explanation:

Answer 2

D.
`-360\,(km)/(h)`

Explanation:

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

`\bar a = (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* (1\,h)/(60\,min)`

`t_(o) = 0.083\,h`

`t_(f) = 9\,min * (1\,h)/(60\,min)`

`t_(f) = 0.15\,h`

If we know that
`t_(o) = 0.083\,h`,
`v_(o) = 60\,(km)/(h)`,
`t_(f) = 0.15\,h` and
`v_(f) = 36\,(km)/(h)`, then the average acceleration of Kelly is:

`\bar a = (36\,(km)/(h)-60\,(km)/(h))/(0.15\,h-0.083\,h)`

`\bar a = -358.209\,(km)/(h^(2))`

The correct answer is D.