Solving for Acceleration in an Emergency Braking Exercise: Kinematics Problem

[tahayassen]

Homework Statement

In an emergency braking exercise, a student driver stops a car traveling at 83 km/h [W] in a time of 4.0 s. What is the car's acceleration during this time?

Homework Equations

The Attempt at a Solution

a = (v2-v1)/t
= 83/4
= 21 m/(s^2) [E]

 

[tiny-tim]

hi tahayassen!

erm …

km/h ​

 

[tahayassen]

Oh... What a dumb mistake. I'm looking at old tests that I've written, and I'm trying to see my mistakes for the upcoming exam!

 

[tiny-tim]

yeah, exam questions can be sneaky …

always check the units! ​