Lecture Notes on Force

Definition and Misconceptions

• Traditional Definition: Force is typically defined as a push or pull upon an object.
• Misconceptions:
  • Stationary objects can have forces acting on them.
  • Movement does not always imply a net force.

Forces on Stationary Objects

• A stationary ball on the ground has forces acting on it:
  • Gravitational Force: Pulls the ball towards the Earth's center.
  • Normal Force: Equal and opposite force from the ground.
• These forces balance out, resulting in a net force of zero, keeping the object at rest.

Forces and Motion

• Net Force: Required for changing the motion of an object.
• When a ball is kicked, an unbalanced force results in movement.
• Friction can stop a moving object by providing an opposing force.
• In the absence of friction and air resistance, an object in motion remains in motion at constant velocity.

Key Concepts

1. Balanced Forces:
   • If net force is zero, a stationary object remains at rest.
   • If net force is zero, a moving object continues at uniform velocity.
2. Unbalanced Forces:
   • Causes an object to accelerate.
   • Change in velocity results from application of an external force.

Force Interaction

• Force is an interaction between objects.
• Example: When you kick a ball, the ball exerts a force on your leg as well.

Conclusion

• Force: A result of interaction, causing push or pull.
• Further exploration of force concepts will be covered in subsequent lectures.