Maximum speed for car rounding unbanked curve with friction

[candflhal]

on his way home from the office, stevens car rounds an unbanked curve that has a radius of 100 m. if the coefficient of friction between the tires and the road is 0.40, what is the fastest speed at which the car can round this curve in miles per hour?

i tried to solve but i just do not understand

 

[candflhal]

this is another problem i need help with

Madison, whose mass is 35.0 kg, climbs the ladder on the slide in her back yard, and slides to the ground at an angle of 30.0⁰ to the horizontal. If the coefficient of sliding friction is 0.15, what is Madison’s acceleration down the slide? Ignore the initial effects of starting friction.

 

[462chevelle]

per the rules you need to post up the equations your trying to use and your attempt at a solution

 

[candflhal]

i do not know what equation I am supposed to use and i hvnt attempted to solve due to me not knowing that

 

[candflhal]

my second problem has to do with friction and slope

 

[haruspex]

If the car has speed v, what centripetal acceleration is needed to make it around the curve? If m is the mass of the car, what lateral frictional force does that imply?
(Pls use a separate thread for unrelated problems.)