🎯 Force is a vector quantity - it has both magnitude and direction.

• The arrow's length represents the magnitude of the force.
• The arrow's direction shows the force's direction.

🎯 Free-Body Diagrams help us visualize and manage forces when situations get complicated.

• It's a handy tool to display all the forces acting on a single body. Let's lay down the rules:
• Represents one body.
• Only forces acting on the body are drawn.
• Force arrows start from the center of mass of the body.
• Forces should be clearly labelled.

• In this scenario, the ball is falling freely under gravity with no air resistance.
• The free-body diagram has one force - gravity. Earth pulls the ball downwards, and we disregard the ball's pull on Earth (because our diagram only includes forces on the ball).

💡 Picture a tennis ball falling straight down when you've dropped it.

• Imagine the same tennis ball now lying still on the ground.
• There are four forces at play here: the weight of the ball (downwards), the Earth's reaction to this weight, the upward force from the ground (because it deforms slightly under the ball's weight), and the ball's reaction to this "spring-like" force.
• But in the free-body diagram, we only care about the forces acting on the ball - its weight (downwards) and the upward force from the ground (the normal force).
• These forces are equal and opposite, so there's no net force, meaning the ball doesn't move!