Find the minimum coefficient of friction needed between the tires and the road to allow a 1500-kilogram racecar to round a curve of radius 75.9 meters if it travels
one lap of the track at a speed of 22.3 m/s?

Suppose that 27 j of work is needed to stretch a spring from its natural length of 6 m to a length of 9 m. (a) how much work is needed to stretch the spring from 12 m to 14 m? j (b) how far beyond its natural length will a force of 78 n keep the spring stretched?