Contact Forces and Pressure

Contact Forces

• Contact forces are forces that act through physical contact between two objects.
• Examples:
  • Normal force (force exerted by a surface on an object)
  • Frictional force (force that opposes motion between two surfaces)
  • Tension force (force exerted by a stretched string or wire)
  • Air resistance force (force that opposes motion through air)

Pressure Calculation

• Pressure is the force per unit area on an object.
• Pressure (P) = Force (F) / Area (A)
• Unit: Pascals (Pa)
• Formula: P = F / A
• Example: A force of 10 N is applied to a surface area of 2 m^2. What is the pressure?
  • P = 10 N / 2 m^2 = 5 Pa

Atmospheric Pressure

• Atmospheric pressure is the pressure exerted by the weight of the air in the atmosphere.
• Also known as barometric pressure.
• Measured in units of pressure (e.g. Pascals, pounds per square inch).
• Standard atmospheric pressure at sea level: 101,325 Pa or 1 atm.
• Atmospheric pressure decreases with altitude.

Non-contact Forces

• Non-contact forces are forces that act without physical contact between two objects.
• Examples:
  • Gravity (force of attraction between two objects with mass)
  • Electromagnetic force (force between charged particles)
  • Magnetic force (force between magnets)
  • Nuclear force (force that holds nuclei together)
• Non-contact forces can act over long distances, unlike contact forces.

Contact Forces

• Contact forces are forces that act through physical contact between two objects, examples include:
  • Normal force, which is the force exerted by a surface on an object
  • Frictional force, which opposes motion between two surfaces
  • Tension force, which is the force exerted by a stretched string or wire
  • Air resistance force, which opposes motion through air

Pressure Calculation

• Pressure is the force per unit area on an object, calculated using the formula: P = F / A
• Unit of pressure is Pascals (Pa)
• Example: A force of 10 N applied to a surface area of 2 m^2 results in a pressure of 5 Pa

Atmospheric Pressure

• Atmospheric pressure is the pressure exerted by the weight of the air in the atmosphere, also known as barometric pressure
• Standard atmospheric pressure at sea level is 101,325 Pa or 1 atm
• Atmospheric pressure decreases with altitude

Non-contact Forces

• Non-contact forces are forces that act without physical contact between two objects, examples include:
  • Gravity, the force of attraction between two objects with mass
  • Electromagnetic force, the force between charged particles
  • Magnetic force, the force between magnets
  • Nuclear force, the force that holds nuclei together
• Non-contact forces can act over long distances, unlike contact forces