Question

A force of newtons is applied to a 20cm^2 surface. The force applied is then increased by f Newtons and the surface area is increased by 5cm^2. Complete the following sentence describing the outcome of the increases.

Answer 1

The pressure is decreased by 15.56%

Answer 2

The pressure decreased by 18%

Explanation:

Given two scenarios:

Step 1: Find the initial pressure

Initial force = 90 Newtons

Initial surface force is applied on = 20 cm²

Initial pressure = initial force/initial surface

*Note: the SI unit for pressure is N/m²

We need to convert cm² to m²

1 cm² = 0.0001 m²

20 cm² = 0.002 m²

Initial pressure = 90/0.002 m²

Initial pressure = 45,000 N/m²

Step 2: find new pressure

New force = 90+5 = 95N

New area = 20+5 = 25 m² = 0.0025m²

New pressure = 95/0.0025 = 38,000

Step 3: find the outcome of the increases by calculating the % change in pressure

% change in pressure = (new pressure - initial pressure)/initial pressure × 100

Thus,

% change in pressure = (38,000 - 45,000)/38,000 × 100

= -7,000/38,000 × 100

= -18.42 ≈ -18%

The outcome of the increase resulted in a decrease in pressure. Thus,

The pressure decreased by 18%