Physics Basics

Key Concepts Covered

• Displacement
• Velocity
• Acceleration
• Projectile Motion
• Newton's Three Laws
• Forces
• Momentum

Distance and Displacement

• Distance: A scalar quantity, it only has magnitude (e.g., 200 miles).
• Displacement: A vector quantity, it includes both magnitude and direction (e.g., 300 miles north).
• Example: John walks 8 meters east and 3 meters west.
  • Total distance = 11 meters.
  • Displacement = 5 meters east.
• Scalar Quantity: Magnitude only.
• Vector Quantity: Magnitude and direction.

Speed and Velocity

• Speed: Scalar, describes how fast something is moving.
• Velocity: Vector, describes speed with direction.
• Example: Car travels 30 meters per second.

Key Formulas

• Average Speed = Total Distance / Total Time.
• Average Velocity = Displacement / Total Time.

Acceleration

• How fast the velocity is changing.
• Positive Acceleration: Speeding up.
• Negative Acceleration: Slowing down.
• Formula: ( a = \frac{\Delta v}{\Delta t} )

Gravitational Acceleration

• Earth's gravitational acceleration = ( -9.8 , \text{m/s}^2 )
• Affects vertical component of velocity (Vy), not horizontal (Vx).

Projectile Motion

• Definition: An object moving under the influence of gravity.
• One-Dimensional: Movement in one direction, typically vertical.
• Two-Dimensional: Movement in both x and y directions.
• Key Points:
  • Vx (horizontal velocity) remains constant.
  • Vy (vertical velocity) is affected by gravity.

Newton's Three Laws

First Law

• An object at rest stays at rest unless acted on by a force.
• An object in motion continues in motion unless acted on by a net force.

Second Law

• ( F_{net} = ma )
• Example: A 10 kg mass with an 80 N force has an acceleration of 8 m/s²._

Third Law

• Not covered in depth, but generally: For every action, there is an equal and opposite reaction.

Forces

• Tension Force: Force acting through a rope.
• Friction: Opposes motion, slows objects down.