Question

Your car gets a flat! You go from 90 kilometers per hour to a stop
in 6 seconds. What is your rate of deceleration? (it's negative)

Answer 1

Answer:

$-4.2 m/s^2$

Explanation:

The acceleration of an object can be found using the equation

$a=\frac{v-u}{t}$

where

v is the final velocity of the object

u is the initial velocity of the object

t is the time taken for the velocity to change from u to v

For the car in this problem:

$u=90 km/h \cdot \frac{1000 m/km}{3600 s/h}=25 m/s$ is the initial velocity

v = 0 is the final velocity (the car comes to a stop)

t = 6 is the time interval it takes  for the car to stop

Substituting, we find the deceleration of the car:

$a=\frac{0-25}{6}=-4.2 m/s^2$

where the negative sign indicates that the car is slowing down.

Answer 2

Answer:

Your car gets a flat! You go from 90 kilometres per hour to a stop in 6 seconds. What is your rate of deceleration? (it's negative!)

-15