how to determine speed with distance and time

[nitrohalic3]

in school we're making co2 cars and mine went 60 feet in .60 seconds and I want to see how fast that is in mph

[Big Dave]

v=d/t

Velocity is the distance traveled divided by the time it took to travel.


BUT, since I'm assuming your vehicle started from a dead stop there's a massive calculus type equation needed to determine the speeds, and will not give you an accurate top speed without a constant rate of accleration.

v=d/t will give you an average though.

[asif2290]

Is that in point 60 or 60 seconds?

--asif2290

[Big Dave]

Ok, so per my calculations your average speed was 68.1 mph. Seems a little on the high side, but I have no clue. Haven't taken physics in years and failed Calc 1 three different times so math isn't my strong suit.

[BobR]

TI83SE, don't fail me now...

Average speed = (distance) / (time)

That's 100ft/sec, or roughly 68.2mph average (exactly, 68.18... repeating, or 750/11). If that was a time-trap run, ~68.2 was the maximum speed. If you measured the run from a standstill, the speed peaked higher than ~68.2, as the slower speeds during acceleration are factored in.

So, Big Dave wins the prize.

[brendan89]

we just made co2 cars like 2 weeks ago, it was fun! to get speed you do distance divided by time, so my calculator told me that you went 100 feet per second. i dont know how to calculate that to mph because last time i tried i got it wrong

the slower speeds during acceleration are factored in

the co2 dragsters dont really "accelerate", their fastest speed is when they take off and then they deccelerate the rest of the way down the drag strip. so that average speed was probly the top speed too because if they are put together correctly they shouldnt slow down much
-Brendan

[nitrohalic3]

ok i was just wondering because my teacher said that was around 120 mph

[MaxxFear]

Here is the drag car that I made when I was in high school! Let's see a pic of yours!

[brendan89]

nice car! i'll post pics of mine whenever i get the film developed (hopefully it wont be long). did you use the pitsco dragster kit? and did you have to cut the axles? they look shorter than mine....
-Brendan

[nitrohalic3]

do yours run along a cable so they stay straight? well ijust made another one and it did like .2 secs in 60 feet. it didnt have wheels but runners which were just the eyelets used to secore the cable. after that everybody copied me. anyways it flew off the track and shattered. i taped it back up though and ran it again but with wheels. i dont have any pics because its mutilated

[djr]

I know how, get a garmin GPS...LOl

[MaxxFear]

Originally posted by brendan89
nice car! i'll post pics of mine whenever i get the film developed (hopefully it wont be long). did you use the pitsco dragster kit? and did you have to cut the axles? they look shorter than mine....
-Brendan

I do not know what kind of kit it was, it has been a long time ago. Most of the other guys use a 2X4 standing up, and I turned mine so that it would lay flat, I can not remember how fast it was. I did not have the fastest, but I had the best looking one!!

[nitrohalic3]

i dont think we used kits. the teacher just handed us a block of wood with a predrilled hole for the co2. we had to cut our own axles though

did you guys race your cars along a cable track?

[brendan89]

Originally posted by nitrohalic3
did you guys race your cars along a cable track?

yes, they went on this special track that had a fishing line down the middle of each lane (called the tether line). i dont remember my time, but some people got .54 seconds
-Brendan