Need someone to check this Physics/Calculus question...

[JohnCU]

A car is traveling at 50mi/h when the brakes are fully applied, producing a constant deceleration of 22 ft/s^2. What is the distance covered before the car comes to a stop?

We're covering anti-derivatives in Calculus now, so here's how I did it.

a(t) = -22 ft/s^2
v(t) = -22t + C
v(0) = 220/3 ft/s so C = 220/3
v(t) = -22t + 220/3
Now, it says the distance covered when the car comes to a stop, so I set v(t) = 0 and got 10/3s for the time.

s(t) = -11t^2 + (220/3)t + C
s(0) = 0 so C = 0.
s(t) = -11t^2 + (220/3)t

s(10/3) = 1100/9 ft traveled before the car stops.

Correct?

 

[dullard]

Please check the definition of acceleration and velocity. You either had a typo or you really goofed big in your understanding of those definitions. Your answer is correct but your equations on the way are incorrect.

 

[TooOne21]

My brain hurts...
I don't ever want to see that stuff again...
I thought after I got my "Piece of Paper" I never needed to look at that stuff again.

 

[DaviDaVinci]

When did OT become a place to find answers t homework problems?

Anyone good at Organic Chem here? I need you to check my solutions.

 

[alexruiz]

Originally posted by: dullard
Please check the definition of acceleration and velocity. You either had a typo or you really goofed big in your understanding of those definitions. Your answer is correct but your equations on the way are incorrect.

How? they seem fine

 

[JohnCU]

Originally posted by: dullard
Please check the definition of acceleration and velocity. You either had a typo or you really goofed big in your understanding of those definitions. Your answer is correct but your equations on the way are incorrect.

How are they incorrect? a(t) is acceleration, v(t) is velocity, and s(t) is position.

acceleration is the second derivative of position, and velocity is the first derivative of position.

 

[Muzzan]

I see no mistakes.

Well, you might want to keep your variables consistent. For example, you say v(t) = -22x + C, i.e velocity is a function of t, but then you switch to x.

 

[JohnCU]

Oh yeah, that was just me thinking quicker than I was typing.

 

[dullard]

Originally posted by: Muzzan
I see no mistakes.

Well, you might want to keep your variables consistent. For example, you say v(t) = -22x + C, i.e velocity is a function of t, but then you switch to x.

Bingo. I said it was likely a typo. But you could have thought that a=dv/dx which whould lead to your equations being functions of x - a major flaw in your understanding.