What is the average velocity during the 5 s interval of the velocity ramp from 0 to 20 m/s?

What is the average velocity during the 5 s interval of the velocity ramp from 0 to 20 m/s?

• A. 5 m/s
• B. 15 m/s
• C. 20 m/s
• D. 10 m/s

Answer: (D)

When velocity changes at a constant rate, the average velocity over a time interval is simply the midpoint between where you start and where you end. Here you start at 0 m/s and end at 20 m/s over 5 seconds, so the average velocity is (0 + 20) / 2 = 10 m/s. You can also see this by area under the velocity–time graph: it's a triangle with base 5 s and height 20 m/s, giving displacement 50 m. Average velocity = displacement / time = 50 m / 5 s = 10 m/s.

When velocity changes at a constant rate, the average velocity over a time interval is simply the midpoint between where you start and where you end. Here you start at 0 m/s and end at 20 m/s over 5 seconds, so the average velocity is (0 + 20) / 2 = 10 m/s.

You can also see this by area under the velocity–time graph: it's a triangle with base 5 s and height 20 m/s, giving displacement 50 m. Average velocity = displacement / time = 50 m / 5 s = 10 m/s.