1. A runner moving at a constant pace of a 4-minute mile rounds a bend with a radius of 36.5 m (standard inside radius for a 400-m oval track). What is the centripetal acceleration of the runner, and what type of force provides the centripetal force on the runner?

2. A standard carousel has a radius of 8 meters. A 75-kg merry-go-round worker stands on the ride's platform 5.8 m from the center, as shown in the figure below. The carousel makes 4 rotations per minute.

a. What is the centripetal acceleration of the worker?

b. What is the force of friction (F_f) necessary to keep her from falling off the platform?

3. A car racing on a flat track travels at 85 mph around a curve with a 500 foot radius. Find the car's centripetal acceleration. What minimum coefficient of static friction between the tires and the road is necessary for the car to round the curve without slipping?