[Physics] Acceleration question

[MonsieuRoberts]

An amusement park ride called the Detonator accelerates passengers straight downward from rest to a speed of 45 Mph in 2.2s. What is the average rate of acceleration during this ride?

This question has me bamboozled guys. BAMBOOZLED. The answer is 9.1 M/S² [S] and I don't know how to get to it.

So, here's my thought process:

"accelerates passengers straight downward from rest to a speed of 45 Mph"

That means we have our V1 and our V2.

V1 = 0 Mph
V2 = 45 Mph [S]

"in 2.2s."

So there's our time.

T = 2.2s

"What is the average rate of acceleration during this ride?"

So, we're solving for A then.

V1 = 0 Mph
V2 = 45 Mph [S]
T = 2.2s
A = ?

The first thing I did was try and convert my Mph (Miles per Hour) values to M/S (Metres per Second):

45 Mph x  1 M/S 
     2.24 Mph  =20.08928571 M/S

Round that off to two SigFigs and you've got 20 M/S.

Then, I tried popping this info into the following equation:

V2 - V1
  T =A

It looks something like this:

Edit: I know what my problem was. Even though I JUST converted my Mph V2 into M/S, I was still putting the 45 MpH [S] into my formula for acceleration. How do you make that mistake two times ina
row? Ugh. I'm gonna follow through just 'cause.

20 M/S - 0 M/S
  2.2S    =9.090909091 M/S² [S]

SigFigs & rounding brings the answer to 9.1 M/S² [S] and everything now makes sense. It's my own inconsistency that's causing me problems. As always.

Thanks for taking a look anyway! Mods ban me forever.

[Adolecent]

Resistance to km is futile.

"Anders Celsius (1701–1744)"

[MonsieuRoberts]

Imperial is a wacky, whimsical system of measurement where nothing makes sense. What's this? It's three of these, 36 of those, and 0.0005 of these!

I hate converting to Imperial so much. I'm not even going to use it, no one developes games in Imperial units.

Well, maybe someone does...but their game is bad and doesn't count.

[luc54]

One good habit into getting into when doing actual physics, is to not use too many intermediate results if necessary. You can plug in all values into actual result formula including the unit conversion to make sure you don't lose too much to rounding errors.

[Adolecent]

Imperial is a wacky, whimsical system of measurement where nothing makes sense. What's this? It's three of these, 36 of those, and 0.0005 of these!

Even the Brits don't use it anymore hehe

[MonsieuRoberts]

One good habit into getting into when doing actual physics, is to not use too many intermediate results if necessary. You can plug in all values into actual result formula including the unit conversion to make sure you don't lose too much to rounding errors.

I had no clue you could pop a conversion into a formula. Wow. My unit only goes up to Gravity as it's just a primer, so I don't have to worry too much about the specifics, but it is good to know how to do this stuff. I'm not going into mechanical engineering, just game design.

I especially love knowing how to convert between m/s and kph. That's actually useful info to know.

[Adolecent]

I especially love knowing how to convert between m/s and kph. That's actually useful info to know.

Remember: 3,6

[Deleted]

Imperial is for cretins. You should chew the assignment up and spit it in your instructor's face.

Agreed. No self-respecting person still uses the imperial system, and the 12 hour time system.

[MonsieuRoberts]

[slickwilly]

The metric system was needed to help the sub 100 IQ folks that are in high numbers in those parts of the world.

[MonsieuRoberts]

The metric system was needed to help the sub 100 IQ folks that are in high numbers in those parts of the world.

So, everywhere but three countries out of almost 200. :P

Moving a decimal around to change units of measurement is just easy. Arbitrary measurement values make no sense to me.

- - - Updated - - -

I passed my test with a 94%! Wee!

[Deleted]

The metric system was needed to help the sub 100 IQ folks that are in high numbers in those parts of the world.

Yet it is the country using the imperial system who has the highest percentage of population being sub 100 IQ.