Lecture Notes: Forces and Motion - Week 2

Overview

• Focus: Forces in Motion
• Reference: Chapter 2 in "A Physical Universe"
• Two-part video series:
  • Part 1: Measuring Motion
  • Part 2: Forces Causing Motion

Core Concepts

• Net Force Required for Change in Motion:
  • An object moves only when a force acts on it (gravitational, magnetic, push/pull).

Describing Motion

• Three Basic Concepts:
  1. Position:
     • Motion relative to a reference point.
     • Change in displacement or distance indicates motion.
  2. Speed and Velocity:
     • Speed: Scalar value (distance/time).
     • Velocity: Vector value (speed with direction).
  3. Acceleration:
     • Change in velocity over time.

Measuring Motion

• Components:
  1. Change in Position:
     • Use rulers, meter sticks, mileage markers.
  2. Change in Time:
     • Use clocks or stopwatches.
• Calculating Speed:
  • Example: Car travels 4 miles in 4 minutes → Speed = 60 mph.

Motion Graphs

• Components of Motion Graphs:
  • Y-axis: Position (meters)
  • X-axis: Time (minutes)
  • Slope: Indicates speed.
  • Average Speed: Total distance/total time.

Speed vs. Velocity

• Speed:
  • Average speed is generally used (e.g., 48 mph average to work).
  • Instantaneous speed varies.
• Velocity:
  • Includes direction (e.g., 50 mph north).
  • Represented as vector quantities.

Acceleration

• Definition:
  • Change in velocity over time (meters/second²).
  • Includes speeding up, slowing down, or changing direction.
  • Example: Car accelerating from 0 to 60 mph.

Gravitational Acceleration

• Measuring Acceleration:
  • Objects speed up while falling.
  • On Earth: Acceleration = 9.8 m/s².
• Projectile Motion:
  • Vertical and horizontal velocities affect distance and time in air.
  • Equation: Height = 1/2 * gravity * time².

Conclusion

• Next Session: Forces and Newton's Laws of Motion
• Prepare by reviewing these concepts and thinking about real-life applications.