You're squeezing a springy rubber ball in your hand. If you push inward on it with a force of 1 N, it dents inward 2 mm. How far must you dent it before it pushes outward with a force of 5 N?

10mm

Explanation:

According to Hooke's law which states that "the extension of an elastic material is directly proportional to the applied force provided the elastic limit is not exceeded. Direct proportionality there means, increase/decrease in the force leads to increase/decrease in extension.

Mathematically, F = ke where;

F is the applied force

k is the elastic constant

e is the extension

from the formula k = F/e

k = F1/e1 = F2/e2

Given force of 1N indents the spring inwards by 2mm, this means force of 1N generates extension of 2mm

Let F1 = 1N e1 = 2mm

The extension that will be produced If force of 5N is applied to the string is what we are looking for. Therefore F2 = 5N; e2=?

Substituting this values in the formula above we have

1/2=5/e2

Cross multiplying;

e2 = 10mm

This shows that we must have dent it by 10mm before it pushes outwards by a 5N force