a substance's density is the same at a certain pressure and temperature, and the density of one substance is usually different than another substance.
From the word compound, the compound machine is already a combination of two or more types of simple machine. Thus, the answer is letter C. Because of its complexity, it is able to perform several other functions than a simple one.
Answer:
Multiply the air pressure by the area of the tabletop.
Explanation:
The relationship between pressure, force and area is given by:

where in this case, p is the air pressure, F is the force exerted and A the area of the tabletop. By re-arranging the equation, we can solve for F, the force exerted:

So, the correct answer is:
The force exerted on the tabletop can be found by multiplying the air pressure by the area of the tabletop.