Question

A steel ball is traveling through water with a speed of x meters per second, where x is positive. The drag force, F, in newtons, N, is: F = 0.5 + 0.004(x + 50)(x-2.5). At what speed in meters per second does the ball have a force of 0.5 N, on it?

Answer 1

x = 2.5m/s.

Explanation:

Given that F = 0.5 + 0.004(x + 50)(x – 2.5), where x is the speed in m/s and F is the force in N. To know the speed, x, with F = 0.5N, we have:

0.5 = 0.5 + 0.004(x + 50)(x – 2.5)

This gives

0.004(x + 50)(x – 2.5) = 0 (after adding –0.5 to both sides).

For the multiplication to be 0, (x + 50)(x – 2.5) = 0 because 0.004 is not equal to 0.

Hence

x = –50 or x = 2.5

Since it is said from the question that x is positive then x = 2.5m/s.