Average Velocity: Definition, Formula, Examples & FAQs

Average velocity is a fundamental concept in kinematics that describes the rate of change of displacement over a given time interval. It is crucial for understanding motion in physics, solving problems in exams, and real-life applications. On this page, learn the definition, formula, solved examples, FAQs, and exam-style MCQs for average velocity.

What is Average Velocity?

• Average velocity is the total displacement divided by the total time taken for that displacement.
• It is a vector quantity: it has both magnitude and direction.
• Formula: Average velocity = Total displacement / Total time
• SI unit: metres per second (m/s)

Example Problem: Calculating Average Velocity

Difference Between Average Speed and Average Velocity

• Average speed = total distance / total time (scalar, always positive).
• Average velocity = total displacement / total time (vector, can be positive, negative, or zero).
• Example: After a round trip (e.g., running a lap), average velocity can be zero but average speed is not.

Frequently Asked Questions (FAQs) about Average Velocity

1. What is average velocity?
   It is the total displacement divided by the total time taken, a vector quantity that indicates the overall rate of change of position.
2. How is average velocity different from instantaneous velocity?
   Average velocity is calculated over a finite time interval; instantaneous velocity is at a specific instant.
3. Can average velocity be zero?
   Yes, if the initial and final positions are the same (like completing a round trip), average velocity is zero.
4. Is average velocity always equal to average speed?
   No. Average speed is based on total distance, while average velocity depends on displacement (which can be less than distance).
5. What is the SI unit of average velocity?
   Metres per second (m/s).
6. Can average velocity be negative?
   Yes, if displacement is in the negative direction relative to your reference.
7. Where is average velocity used in real life?
   Used in travel planning, navigation, and physics problems involving motion.
8. What is the formula for average velocity with varying speeds?
   Use the displacement between starting and ending points divided by the total time, not just the mean of speeds.
9. Why is average velocity important in physics?
   It helps analyze motion, solve kinematics problems, and understand direction-dependent movement.
10. How do you calculate average velocity from a velocity-time graph?
    The slope of the displacement-time graph, or the area under a velocity-time graph divided by time.

Practice MCQs: Average Velocity

1. A car travels 80 km north in 2 hours, then 60 km south in 1 hour. What is the average velocity?
   a) 20 km/h north
   b) 40 km/h north
   c) 13.3 km/h north
   d) 0 km/h
2. Average velocity is always:
   a) Positive
   b) Zero
   c) Negative
   d) Depends on displacement
3. If a runner completes a lap of 400 m track in 100 s, what is the average velocity?
   a) 4 m/s
   b) 0 m/s
   c) 2 m/s
   d) 1 m/s
4. Which quantity is needed to calculate average velocity?
   a) Total time
   b) Total displacement
   c) Both a and b
   d) Initial speed only
5. If total displacement is negative, the average velocity is:
   a) Positive
   b) Zero
   c) Negative
   d) Cannot be determined

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