This document discusses force, pressure, and how pressure works in liquids and air. It defines pressure as the amount of force acting on a unit area, and explains that pressure depends on both the force applied and the surface area. It notes that in liquids, pressure is transmitted equally in all directions and increases with depth. It also describes how air has mass and particles that collide, creating air pressure that presses down on surfaces and decreases with increasing altitude due to lower air amounts.

1. CHP: 13 Physics

3. Force and Pressure are NOT the same thing
• Force: is the total impact of one object on another.
• Pressure:is the amount of force acting on an area.

4. • Describes how a force is spread over an area
• It is a measure of how much force is acting on a certain
area.

7. Pressure = Force / Area
Newton per metre squared = Newton / metre squared
N/m2 = N/m2
Another equivalent unit is used for N/m2, Pascal (Pa)

8. Pressure depends on 2 factors:
• Forces acting – Increasing the force will
increase the Pressure.
• Area of surface – Decreasing the area of the
force will increase the Pressure.

10. Pressure in Liquids
• Pressure is transmitted throughout the liquid.
•Pressure acts in all direction.
• Pressure increases with depth.

18. • Pressure in a liquid is transmitted equally and
throughout the liquid.

24. 1)Air has mass. Therefore air has weight.
2)Air has particles that are continually moving and colliding with things on Earth.
These collisions produce air pressure.
3)Air presses down all things in the Earth’s surface. The pressure exerted by air
is known as Air pressure or Atmospheric pressure.
4)The features of Air pressure are:
a) acts in all directions
b) changes from one place to another
c) decreases the higher you go above the ground level. This feature exists
because at high place, the amount of air decreases. This explains why the air
pressure on the top of a mountain is lower than at the foot of the mountain.

28. • Atmospheric pressure can be measured with a mercury barometer.
• The column of mercury is held up by air pressure.
• As the air pressure varies from day to day the height of the mercury
also varies