Instantaneous speed and velocity

• What is the problem with average speed in measuring motion?

  It does not indicate whether the speed changes over the total time period.
• What is the purpose of using instantaneous speed or velocity?

  To overcome the limitations of average speed by measuring speed at a specific moment.
• How is instantaneous velocity defined?

  It is the velocity of an object measured over a very short time.
• What does the graph of displacement versus time show for an object?

  • Variation of displacement \( x \) with time \( t \)
  • Points A, B, C, and D represent different velocities
  • Maximum velocity occurs at point B
• What is the average speed of the journey from A to C if the total distance is 380 km and the total time is 4200 seconds?

  Average speed is calculated as total distance divided by total time.
• How do you determine the average velocity from A to C given the total displacement and total time?

  Average velocity is total displacement divided by total time.
• Why is the average speed not the same as the magnitude of the average velocity?

  Because average speed is a scalar quantity while average velocity is a vector quantity.
• What is the conversion factor used in the problem where 1.0 cm equals 904 m?

  1. 0 cm = 904 m
• If the average speed is calculated as \( 9.6 \times 50 \), what is the result in meters per second?

  The result is \( 480 \text{ m/s} \).
• What is the average velocity calculated from the total displacement of 380 km and total time of 4200 seconds?

  Average velocity is \( \frac{380 \text{ km}}{4200 \text{ s}} \approx 0.0952 \text{ km/s} \) or \( 95.2 \text{ m/s} \).
• What does the notation \( 9.6 \times 50 \) represent in the context of average speed calculation?

  It represents the multiplication of average speed by time to find distance.
• What is the total displacement in the journey from A to C?

  The total displacement is 380 km.
• What is the total time taken for the journey from A to C?

  The total time taken is 4200 seconds.
• What is the significance of the points A, B, C, and D on the displacement-time graph?

  They indicate different velocities of the object at those points.
• How can you determine which point on the graph corresponds to maximum velocity?

  By identifying the steepest slope on the displacement-time graph.