Peoples Physics Concepts

4.6. Pressure and Force http://www.ck12.org

4.6 Pressure and Force

• Explain the difference between pressure and force.


• Calculate the pressure in a variety of problems.

Students will learn the difference between pressure and force and how to calculate the pressure in a variety of
problems

Key Equations

P=FA; Pressure is a force exerted over some area

Guidance

Pressureis often confused with force. Pressure is force spread out over an area; a small force exerted on a very

small area can create a very large pressure; i.e., poke a pin into your arm!

Example 1

How much pressure does a 340-g Coke can exert on a table if the diameter of the can is 8.0 cm?

Question: P=?[Pa]

Given: m= 340 grams= 0. 340 kg

diameter= 8. 0 cm= 0. 08 m

g= 10 m/s^2

Equations: P=FAArea of a circle:A=π·r^2

Plug n’ Chug: P=FA=πmg·r 2 =

( 0. 340 kg)

(

(^10) sm 2
)
π(^0.^082 m)^2

=

(

3. 4 kgs· 2 m

5. 0 × 10 −^3 m^2

)

= (^680) mN 2 = 680 Pa