# physics hey bob

posted by .

you help me solve this problem. but how am i suppose to if i don't know the mass of the car?

on a level road the stopping distance for an automobile is 35.0m for an initail speed of 90 km/hr what is the stopping distance of the same automobile on a simalr road with the slope 1:10

physics - bobpursley, Saturday, October 30, 2010 at 7:42am
Assume the coefficent of friction is the same.

F=mu*Normal force=ma
a= normalforce*mu/mass

solve for mu on the level road, knowing normalforce is mg.

Then, knowingmu, look at the slope
normal force=mg*SinTheta
Vf^2=Vi^2+2mgSinTheta*mu/m * d
solve for distance.

since Theta is a small angle, SinTheta=TanTheta= 1/10

• physics hey bob -

YOu are supposed to realize that you have m/m and it divides out.

normalforce*mu/mass= mgSinTheta*mu/m

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