What is the average deceleration during braking?

[needhelp83]

The driver of an automobile traveling at 80 km/h suddenly slams on the brakes and stops in 2.8 s. What is the average deceleration during braking

Velocity of driver=(80 km/h)(1 h/3600 s)(1000 m/1 km)=22.22 m/s

average acceleration=change of velocity/time elapsed
Acceleration = final velocity - initital velocity / time
Acceleration=(0 - 22.22 m/s)/2.8 s=-7.94 m/s/s

Average deceleration= 7.94 m/s/s

Just double checking

 

[radou]

You got that one right.

 

[needhelp83]

Thank you. Just trying to make sure everything was setup correctly