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**Grade 12 physics help please!!**

## Homework Statement

2. A car is travelling along the QEW. It leaves the highway on a turn that has a radius of 90.0m.

a. If the coefficient of maximum static friction between the tires and the road is 0.89, and typical speeds are 100km/h, what is the minimum angle the road needs to be banked at so the car doesn’t go sliding off the road?

b. If the coefficient of maximum static friction was reduced to 0.40 because of rain or an oil spill, what is the new minimum angle that the road should be banked at to avoid sliding off the road?

3. A road is banked at an angle of 12° and the radius of the curve is 75m. If the coefficient of friction between tires and dry concrete is 0.9 and it reduces to 0.6 in rain, what do you feel the posted speed limit should be?

## Homework Equations

F

_{net}= ma

_{c}

a

_{c}= mv

^{2}/r

a

_{c}= 4∏

^{2}r/T

^{2}

## The Attempt at a Solution

for number 2, I just don't know. :(

for the third, I think I can use mv

^{2}/r, but I'm not sure how to solve without mass or velocity.

Any help would be greatly appreciated!