Solving for Acceleration in an Emergency Braking Exercise: Kinematics Problem

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In an emergency braking scenario, a student driver stops a car traveling at 83 km/h in 4.0 seconds. The initial attempt to calculate acceleration used the formula a = (v2 - v1)/t, leading to an incorrect unit conversion. The correct acceleration calculation requires converting the speed from km/h to m/s before applying the formula. The discussion emphasizes the importance of checking units in physics problems to avoid mistakes. Proper unit conversion is crucial for accurate results in kinematics.
tahayassen
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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]
 
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hi tahayassen! :smile:

erm :redface: …

km/h :wink:​
 
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!
 
yeah, exam questions can be sneaky …

always check the units! :smile:​
 

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