Lecture Notes: Contact and Non-Contact Forces

Introduction

• Definition of force: A push or pull that acts on an object due to interaction with another object.
• Characteristics of forces:
  • Have both magnitude (size) and direction.
  • Vector quantity.
  • Unit of force: Newton.

Types of Forces

• Forces are categorized into two types:
  • Contact Forces
  • Non-Contact Forces

Contact Forces

• Occur when two objects are physically touching.

Examples of Contact Forces

1. Tension in a Rope

   • Example: Tug of war, where the force of tension pulls on the soldiers.

2. Friction

   • Example: Airplane landing on water; friction between water and airplane slows it down.

3. Air Resistance

   • Example: Skydiver; air particles collide with parachute causing air resistance to act upwards.

4. Normal Contact Force

   • Example: Lamp on a table; the lamp exerts a downward force (weight) and the table exerts an upward force (normal contact force).
   • Occurs only when two objects are in direct contact.

Non-Contact Forces

• Occur when two objects are physically separated.

Examples of Non-Contact Forces

1. Gravitational Force

   • Attracts objects to one another.
   • Example: Earth and the International Space Station.

2. Electrostatic Force

   • Force between charged objects.
   • Opposite charges attract, same charges repel.
   • Objects remain separated physically.

3. Magnetic Force

   • Experienced by objects in a magnetic field.
   • Will be explored in detail in future lectures.

Additional Resources

• Questions on contact and non-contact forces can be found in the revision workbook available through the provided link.

Note: The lecture suggested more exploration on topics like weight, normal contact force, and magnetic force in future videos.