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how do i calculate speed in MPH ...???

Good morning AB'ers and a very happy bank holiday to you all.

My question for you brainboxes is this:

If my 1:10th scale model Radio controlled car covers 8.8 metres in 0.58 of a second, can anyone tell me how fast it's travelling in MPH....??

And if possible, how do i calculate this for future 'speed trials' ?

Many thanks all.
Eddie

harley_Husky Sun 24/08/08 12:52

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samfonzo
Sun 24/08/08
12:59

100 miles per hour = 160 kilo meter per hour so
divide kmps/1.6 = miles

ie 80kpms/1.6 = 50mph

harley_Husky
Sun 24/08/08
13:25

Question Author

Many thanks Samfonzo.

Have a good day :0)
Eddie

748rhydhir
Sun 24/08/08
17:49

8.8m in 0.58secs is14.96m/s=898m/hr=0.57mph.
if my maths is correct.

harley_Husky
Sun 24/08/08
20:02

Question Author

Fabulous.
Thanks very much.

57mph is mightily impressive. I'm on a brushless system running an 8.4v nicad battery pack. Wait untill 11.4v LiPo ... 76mph apparently - Motorway speeds !!!

Top banana.
Eddie

north star
Sun 24/08/08
22:01

My maths gives me :-

8.8 m in 0.58 s gives 15.2 m/s gives 54 720 m/hr = 54.72 km/hr

54.72 x 0.6215 = 34.01 miles/hr

mibn2cweus
Mon 25/08/08
05:37

First calculate meters per second . . .
Divide distance in metres: 8.8
by time in seconds: 0.58
to get metres per second: 15.1724138

Then to convert m/s to mph . . .
Multiply by: 2.237
to get: 33.94 mph

748rhydhir
Mon 25/08/08
15:02

my maths is incorrect.found out there are 3600secs in an hour.
approx 34mph

mibn2cweus
Mon 25/08/08
17:56

Speed is proportional to distance divided by time d/t
88cm/s = 19.685mph

Using 88cm for the reference distance and 19.685 as the corollary conversion factor . . .

19.685 / 1 sec. = 19.685 mph
19.685 / 0.5s = 39.37 mph
19.685 / 1.5s = 13.12 mph
19.685 / 0.58s = 33.94 mph

If it is convenient to slightly increase the reference distance from 8.8 to 8.94 metres the conversion factor for this distance rounds out to a nice even 20.0 . . .

20 / seconds = mph!

Even using this simplified formula without modifying the reference distance of 8.8 metres introduces an error of less than 2%.

Incidentally (as I’m sure your aware) at 1/10 scale 8.8 metres in 0.58 seconds corresponds to 339.4 mph!

1 metre / second = ~ 2.237 mph

mibn2cweus
Mon 25/08/08
20:02

. . . and yes, 88cm should have read 880cm (8.8 metres) in the previous posting.

harley_Husky
Sat 30/08/08
18:42

Question Author

Thanks you Boffins !! LOL\

Hope we're all having a good weekend !

Best regards
Eddie

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