Friction coefficient?

The friction coefficient between an athelete's ahoes and the ground is 0.90 . Suppose a superman wears these shoes and races for 50 m. There is no upper limit on his capacity of running at high speeds . What will be the minimum time that he will have to take in completing the 50 m starting from rest ?

Friction coefficient?
Assume superman's mass = m





Friction force developed by shoes: (g = 9.8 m/s^2)


Ff = m * g * 0.9





Acceleration from force:


F = m * a





Equate the forces such that F = Ff, solve for acceleration:


m * a = m * g * 0.9


a = 8.82 (m/s^2)





Determine the time required to go 50 m:


x = (1/2) * a * t^2


50 = 0.5 * 8.82 * t^2


t = 3.367 seconds





Tada!



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