Which material is very strong and tough but shows very little elongation as it absorbs energy? a. spider silk b. rubber c. kevlar® d. concrete

C) Kevlar

Explanation:

Kevlar is a fiber which is heat resistance and very strong.

This is stronger than steel so it is used in many purpose due to its lower weight.

It is used to design the special suits of army and commando. Since it is heat resistant so it is also used as the suits to work at high temperature industries.

Also this fiber has very small tendency to expand so the elongation in this fiber is very small when we apply some force on it.

So in this type of fiber the strength is more and the stretch is less

So correct answer will be

C) Kevlar

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.