Question

A force of 65 newtons acts on an area of 12 cm. The force is increased by 20 newtons. the area is increased by 5 cm² Helen says, "the pressure decreases by less than 20%" is Helen correct?

Answer 1

Yes. See below.

Explanation:

In the first case the pressure = 65/12 = 5.41667 N per cm^2.

Then the pressure per cm^2 = 85/17 = 5 N per cm^2.

Decrease = (5.41667 - 5) / 5.416667

= 0.41667/ 5.41667

= 0.077

= 7.7 %.