## caculating tractive force (i need a formula)

i ve got the following question from my motor vechile diploma

kerbside weight 1360kg
rolling resistance 140N per 1000kg
frontal area 2m(squared)
drag coefficient 0.025

caculate the total tractive resistance when the car travels at 70 km/h on a level road?

what i need is the formula to work out tractive resistance ive searched for about 3 hours on the net but no luck.

any help appreciated

dan
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 Blog Entries: 1 Recognitions: Gold Member Science Advisor Staff Emeritus Firstly, ask yourself what is tractive resistance?
 is it traction

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## caculating tractive force (i need a formula)

 Quote by dan_bighit is it traction
Which is what in terms of the forces acting on a vechicle?
 drag force

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 Quote by dan_bighit drag force
Which would include the rolling resistance of the wheels and the fluid friction from the air, yes? So can you write down an equation for these two forces?
 i can work out the rolling resistance and air resistance which is rolling resistnce = 190.4N air resistance = 452.76N what i need is a formula so i can caculate the total tractive force
 Blog Entries: 1 Recognitions: Gold Member Science Advisor Staff Emeritus So, if the tractive force is the total or sum of all the drag forces acting on the vechicle, what do you think you should do now?

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 Quote by dan_bighit add them together
Sounds good to me
 ok heres the full question kerbside weight 1360kg rolling resistance 140N per 1000kg frontal area 2m(squared) drag coefficient 0.025 caculate the rolling resistance of the car? caculate the gradient resistance when the car climbs a gradient of 1/20 caculate the air resistance of the car when it is travelling on a level road at 100 km/h? caculate the total tractive resistance when the car travels at 70 km/h on a level road? ive answered the top 3 questions but havent used drag coeeficcient and i thought that might come in to tractive resistance but obvisily not. so where would that come in to surly they couldent of just told you it for the sake of it.
 Blog Entries: 1 Recognitions: Gold Member Science Advisor Staff Emeritus You should have used the drag coefficient in calculating the air resistance of the car.
 i got the formula formula form here http://www.webtec.co.uk/techinfo/equ...qnfr/eqn01.htm i think i see where ive gone wrong because ive worked out using 0.0462 when it should have been 0.025 if you could just clarfy this ill be happy thanks for your help
 Blog Entries: 1 Recognitions: Gold Member Science Advisor Staff Emeritus My best guess is that you are required to use Stoke's-type formula to calculate the drag; $$F = -bAv$$ where b is your drag coefficient. And we usually work in SI units, m, m/s2, N etc.
 im abit confused now , what does the v mean. so that formula on the website is wrong ?

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