Speed and Motion

Comparing Speeds of Objects

• Two Objects: Object 1 and Object 2 moving along the same path.
• Observation: By comparing motion, Object 1 moves faster as Object 2 lags behind.
• Conclusion: Speed of Object 1 > Speed of Object 2.

Definition and Calculation of Speed

• Speed: Physical quantity indicating how fast something is moving.
• Components to Know Speed:
  1. Distance traveled.
  2. Time taken to travel that distance.

Example: Cars on a Straight Road

• Type of Motion: Rectilinear motion (motion in a straight line).
• Scenario:
  • Blue Car: Covers the path in 30 seconds.
  • Red Car: Covers the same path in 40 seconds.
• Comparison: Blue Car moves faster than Red Car because it covers the distance in less time.

Speed Calculation

• Formula: Speed = Distance / Time.
• Example: Path length = 420 meters.
  • Blue Car Speed: 420m / 30s = 14 m/s.
  • Red Car Speed: 420m / 40s = 10.5 m/s.
  • Third Car: 420m / 20s = 21 m/s (fastest).

Units of Speed

• Common units include:
  • Meters per second (m/s).
  • Kilometers per hour (km/h).
  • Miles per hour (mph).
  • Feet per minute.
• Example: Car's speed of 14 m/s.

Average Speed

• Concept: Average speed = Total distance / Total time taken.
• Example: Car A covers 420 meters in 30 seconds.
  • Average speed = 420m / 30s = 14 m/s.
  • Not constant throughout; car could vary in speed.

Important Insights

• Average speed does not mean constant speed.
• Speed can vary during the travel; average speed gives an overall measure.

Future Topics

• Detailed study of speed units.
• More on average speed, including variable speeds.