Describe three ways you commonly use elastic force, in each case, identify the job done by elastic force.

1. The rubber band that used to tie hair are the most used item that does elastic force. Since hair is too big it will cause the rubber to be stretch, elastic force tries to make it size come back so it will apply force inside.
2. Spring bed has spring inside them. The spring will try to maintain their length so when there is any weight that tries to shorten them, they will apply force outward.
3. Earlier clock use spring to move their hands. This type of clock doesn't need electricity because the force is made by elastic force

Answer: fn = wcos50 = 38.89(9.81)(cos50) = 245.23 n