Problema Solution

The force needed to keep a car from skidding on a curve varies inversely as the radius of the curve and jointly as the weight of the car and the square of the speed. If 126 lb of force keeps a 1800-lb car from skidding on a curve of a radius 600 ft at 25 mph, what force would keep the same car from skidding on a curve radius 850 ft at 45 mph?

Answer provided by our tutors

let


F = the force


R= the radius of the curve


W = the weight of the car


V = the speed


The force needed to keep a car from skidding on a curve varies inversely as the radius of the curve and jointly as the weight of the car and the square of the speed:


F = k(W * V^2)/R, where k is constant


126 lb of force keeps a 1800-lb car from skidding on a curve of a radius 600 ft at 25 mph we have:


F = 126 lbs

W = 1800 lbs

R = 600 ft

V = 25 mph


126 = k(1800 * 25^2)/600


by solving we find k:


k = 0.0672


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now we know that:


F = 0.0672(W * V^2)/R


R = 850 ft

V = 45 mph

W = 1800 lbs


F = 0.067(1800 * 45^2)/850


F = 287.31 lbs


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