P11: Forces and Pressure

• Pressure is defined as the amount of force applied per unit area.
• Pressure

  Decreases the higher up you go as there are less air molecules exerting a downward force, therefore less pressure
• Pressure

  Increases as you go deeper in water as there are more water molecules exerting a downward force on an object
• Less air molecules mean less weight being exerted, causing atmospheric pressure to decrease the higher up you go
• Weight

  Weight (W) = Mass (M) x Gravitational field strength (g)
• SI unit for pressure

  Pascal (Pa)
• Atmospheric pressure decreases with altitude due to less air above exerting downward force on Earth's surface