Velocity — Science definition

Speed in a specific direction, like 60 km/h north.

Where it is taught

In use

Velocity takes speed and adds one crucial extra piece of information: direction.

Speed, Velocity & Acceleration

Questions using velocity

Problem 1

Explain the difference between speed and velocity using an example.
Answer and explanation

Speed only tells you how fast something is moving, like 50 km/h. Velocity tells you how fast AND in what direction, like 50 km/h north. Two cars traveling the same speed in opposite directions have the same speed but different velocities.

Problem 2

A student walks 30 m east then 30 m west in 40 s. Find average speed and average velocity. Explain the reasoning in your own words.
Answer and explanation

Average speed 1.5 m/s; average velocity 0 m/s.

Total distance=60 m; speed=60/40=1.5 m/s.

Displacement=0 m; average velocity=0/40=0 m/s.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 3

Velocity changes from 2 m/s east to 10 m/s east in 4 s. Calculate average acceleration.
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

(10−2)/4=2 m/s² east, assuming east is positive.

Problem 4

Right is positive. A cart changes velocity from −2 to −8 m/s in 3 s. Calculate average acceleration and explain whether it speeds up or slows down.
Answer and explanation

(−8−(−2))/3 = −2 m/s². It speeds up toward the left because speed rises from 2 to 8 m/s.

Subtract signed velocities before dividing.

Compare velocity direction with acceleration direction.

Response criteria

  • Calculate −2 m/s².
  • Explain leftward motion.
  • Reject negative-always-slows.

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