HighSchoolScience101: Forces in Physics

Introduction

• Focus on forces in physics
• Definition of force: An interaction that causes an object to:
  • Start moving
  • Speed up
  • Stop moving
  • Slow down
  • Change direction
  • Change shape

Types of Forces

Contact Forces

• Require physical contact between two surfaces
  • Example: Applying force to putty to change its shape.
• Friction is another example of a contact force.
  • Recommended to watch a video on friction for more detail.

Non-Contact Forces

• Do not require physical contact
  • Example: Magnets
    • Operate through an invisible field affecting other objects within it.
    • Magnetic objects are often made of iron, nickel, or cobalt.
    • Electrons align in one direction, creating a magnetic field.
    • Each magnet has a North pole and a South pole.
      • Like poles repel (North-North, South-South)
      • Opposite poles attract (North-South)
• Another example: Static Electricity
  • Occurs when electrons jump between objects
  • Object losing electrons becomes positive; gaining object becomes negative.
  • Example: Rubbing a cloth against a balloon transfers electrons, attracting other objects.

Gravity

• Affects us daily; associated with large masses (planets, moons, stars)
• Isaac Newton's Universal Law of Gravitation:
  • Every mass has a gravitational field.
  • Gravitational pull is small between insignificant masses (e.g., computer and person).
• The strength of gravitational attraction depends not only on mass but also on distance:
  • Greater distance = weaker gravitational field.

Conclusion

• Covered what a force is and different types of forces.
• Mention of balanced and unbalanced forces for future discussion.
• Thank you for watching!