Finding constant acceleration, unit difficulty

AI Thread Summary
The discussion revolves around calculating the acceleration of an Indy 500 race car, which increases its velocity from 4 m/s to 36 m/s over 4 seconds. The correct formula for acceleration is applied, leading to the equation a = (final velocity - initial velocity) / time. A common misunderstanding arises regarding unit cancellation; while the numerical values can be simplified, the units must be correctly represented as m/s² for acceleration. The clarification emphasizes that both time units remain in the denominator, confirming that the final answer is indeed 8 m/s². This highlights the importance of maintaining proper units in physics calculations.
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Homework Statement


An Indy 500 race car's velocity increases from 4m/s to 36m/s over a 4 second time interval. What is its acceleration? 4m/s is the initial velocity, 36 m/s is the final velocity, and time is 4 seconds.

Homework Equations


final velocity = initial velocity + (acceleration x time)[/B]

The Attempt at a Solution


36m/s = 4m/s + a(4s)
32m/s = a(4s)
a = 8?[/B]

Here's my problem. I know how to work out the equation and solve for acceleration. However, when you divide 32m/s by 4 seconds, I thought that you canceled the units. Which means you would be left with 8 meters (because seconds cancel out). However, I'm aware the correct answer is 8m/s^2 because acceleration is always squared.

Can someone explain my fundamental misunderstanding? It's so simple, but It's really confusing me.
 
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You cannot cancel the units, both time units are in the denominator:

1 m/s / (1 s) = 1 ((m/s)/s) = 1 m/s^2

just as (1/2)/2 = 1/4 and not (1/2)/2 = 1.
 
Orodruin said:
You cannot cancel the units, both time units are in the denominator:

1 m/s / (1 s) = 1 ((m/s)/s) = 1 m/s^2

just as (1/2)/2 = 1/4 and not (1/2)/2 = 1.

Thank you so much, I knew I was making an elementary mistake. I'm an idiot.
 
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