Question

A driver brings a car to a full stop in 2.0 s. If the car was initially

traveling at 22 m/s, what is the acceleration?
a -17 m/s2
b 27 m/s2
c 7 m/s2
d –11 m/s2

Answer 1

`\boxed {\boxed {\sf D. \ -11 \ m/s^2}}`

Step-by-step explanation:

Acceleration can be found by dividing the change in velocity by the time.

`a=(v_f-v_i)/(t)`

where Vf is the final velocity, Vi is the initial velocity, and t is the time.

Since the car came to a complete stop, it's final velocity was 0 meters per second.

The initial velocity was 22 meters per second.

The time was 2.0 seconds.

`v_f=0 \ m/s\\v_i=22 \ m/s\\t= 2.0 \ s`

Substitute the values into the formula.

`a=(0 \ m/s-22 \ m/s)/( 2.0 \s )`

Subtract in the numerator first.

• 0 m/s- 22 m/s = -22 m/s

`a=(-22 \ m/s)/(2.0 \ s)`

Divide.

`a= -11 \ m/s^2`

The acceleration of the car was -11 meters per square second. The negative acceleration indicates slowing down/stopping.