Does anyone understand physics?

Anton created a chart listing different types of materials.which best complete the chart? (a)x: copper y: glass(b)x: rubber y: copper(c)x: paper y: silicon(d)x: silicon y: glass

Dry ice is solid carbon dioxide that is used in the transport of food and medicine. dry ice becomes a gas at –78.5°c without becoming a liquid first.

Suppose you use a machine that gives you a mechanical advantage of 2 to achieve an output force of 30newtons what must the input force be