Lecture Notes on Basic Physics Concepts

Topics Covered

Distance: How far something has traveled (scalar quantity).
- Example: Distance between two cities can be 100 miles.
- Always positive.
Displacement: Difference between the final and initial position, includes direction (vector quantity).
- Example: If John walks 8 meters east and 3 meters west, his total distance traveled is 11 meters but his displacement is 5 meters east.
- Displacement = Final Position - Initial Position.
- Displacement can be positive or negative based on direction.

Scalar Quantity: Only has magnitude (e.g., distance, speed).
Vector Quantity: Has both magnitude and direction (e.g., displacement, velocity).

Speed: How fast something is moving (scalar quantity).
- Example: A car traveling at 30 meters per second.
- Formula: speed (v) = distance (d) / time (t).
- Speed is always positive.

Velocity: Speed with direction (vector quantity).
- Example: A train moving at 30 meters per second west.
- Can be positive or negative.
- Average velocity formula: average velocity (v) = displacement (d) / time (t).

Average Speed: Total distance divided by total time.
- Formula: average speed (v) = total distance (d) / total time (t).
Average Velocity: Displacement divided by total time.
- Formula: average velocity (v) = displacement (d) / total time (t).

Acceleration: How fast the velocity is changing (vector quantity).
- Example: Sports car vs. truck acceleration.
- Positive acceleration increases velocity; negative acceleration decreases velocity.
- Formula: acceleration (a) = (final velocity (vf) - initial velocity (vi)) / time (t).

Gravitational Acceleration: Acceleration due to gravity, on Earth g = -9.8 m/s^2.
- Affects vertical velocity (Vy), not horizontal velocity (Vx).
- Example: Ball dropped from rest or thrown upward.

Projectile Motion: Object moving under the influence of gravity.
- One-dimensional projectile motion: vertical direction only.
- Two-dimensional projectile motion: both horizontal (x) and vertical (y) directions.
- Horizontal Velocity (Vx): Constant, unaffected by gravity.
- Vertical Velocity (Vy): Changes due to gravitational acceleration.
- Formula: Vertical velocity changes by -9.8 m/s every second.

First Law: An object at rest remains at rest, and an object in motion continues in motion unless acted upon by a force.
- Example: Box at rest needs a push/pull force to move.
Second Law: The net force acting on an object is equal to the mass of the object times its acceleration (F = ma).
- Example: 10 kg box with an 80 N force has an acceleration of 8 m/s^2.
Third Law: For every action, there is an equal and opposite reaction (not covered in detail in transcript).