A scooter moves along a straight road and its speed changes uniformly during a short test run. Study the situation and answer the following questions.
(a) Define average velocity of a body moving along a straight line.
(b) The scooter increases its speed uniformly from 10m/s to 30m/s in a certain time interval. A student claims that its average velocity during this interval must be 20m/s. State the specific condition that makes the student’s claim correct and justify your answer with suitable reasoning. Do not perform any numerical calculation.
(c) Explain why the claim in part (b) may not hold if the change in speed is not uniform throughout the interval.