If a curve with a radius of 79m is perfectly banked for a car traveling 71 km/h , what must be the...?
If a curve with a radius of 79m is perfectly banked for a car traveling 71 km/h , what must be the coefficient of static friction for a car not to skid when traveling at 89km/h?
Yes, It is asking for the coefficient of static friction
- SteveLv 77 years agoFavorite Answer
Bank angle Θ = arctan[v²/(Rg)] = 26.675°
For 89 k/h,
µ = [V² - RgtanΘ]/[Rg + V²tanΘ] = 0.205Source(s): Free body diagram My 'cheat sheet' of physics formulae
- Anonymous7 years ago
trick question? does it specifically say static friction?
mu N is friction force, mu N r is frictional torque.
so if friction is = to the force outward, then mu N r = m a r
- CuglierLv 67 years ago
It is perfectly banked at v=71km/h=19.72m/s..R=79m
f=N*µ...N=mg cosα *µ.......µ.=tanα =senα /cosα
m*v2/R=mg*cosα *µ...v2/R=g.senα ...sen α =v2/Rg = 0.5
then α =30° ...µ=tan α =0.5773
Now at v=89km/h=24.72 m/s
the coefficient of static friction is:
mv2/R =mg*cosα*µ .......µ.st=v2/(Rg* cos30°)=0.91 Answer
µ= 0.5773<µ.st= 0.91
Hope this helps