Science: Forces and Pressure

Science: Force and Pressure

Force

• A push or pull that causes an object to change its motion or shape
• Measured in Newtons (N)
• Can be either:
  • Contact force: occurs when two objects are in physical contact (e.g. friction, normal force)
  • Non-contact force: occurs when objects are not in physical contact (e.g. gravity, magnetic force)

Types of Forces

• Gravity: force of attraction between two objects with mass
• Friction: force that opposes motion between two surfaces in contact
• Normal force: force exerted by a surface on an object that is in contact with it
• Tension: force exerted by a stretched string or wire
• Air resistance: force that opposes the motion of an object through the air

Pressure

• Force per unit area
• Measured in Pascals (Pa) or pounds per square inch (psi)
• Calculated using the formula: Pressure = Force / Area
• Depends on:
  • Force applied
  • Surface area of the object

Effects of Pressure

• Increases with:
  • Increase in force
  • Decrease in surface area
• Decreases with:
  • Decrease in force
  • Increase in surface area
• Examples:
  • High pressure at the bottom of a deep swimming pool
  • Low pressure at high altitudes

Science: Force and Pressure

Force

• Defined as a push or pull that causes an object to change its motion or shape
• Measured in units of Newtons (N)
• Classified into two types:
  • Contact forces: occur when two objects are in physical contact (e.g. friction, normal force)
  • Non-contact forces: occur when objects are not in physical contact (e.g. gravity, magnetic force)

Types of Forces

• Gravity: a force of attraction between two objects with mass
• Friction: a force that opposes motion between two surfaces in contact
• Normal force: a force exerted by a surface on an object that is in contact with it
• Tension: a force exerted by a stretched string or wire
• Air resistance: a force that opposes the motion of an object through the air

Pressure

• Defined as force per unit area
• Measured in units of Pascals (Pa) or pounds per square inch (psi)
• Calculated using the formula: Pressure = Force / Area
• Influenced by:
  • Force applied
  • Surface area of the object
• Greater pressure results from:
  • Increasing the force
  • Decreasing the surface area
• Lower pressure results from:
  • Decreasing the force
  • Increasing the surface area

Effects of Pressure

• Examples of high pressure:
  • At the bottom of a deep swimming pool
• Examples of low pressure:
  • At high altitudes