Question

what is the difference between speed and velocity?

a. velocity measures an objects rate and direction of motion, and speed measures rate only.
b. velocity and speed both measure an objects change in position, but velocity only depends upon the objects speed.
c. speed measures an objects change in position per unit time, while velocity measures an objects change in speed per unit time.
d. speed measures an objects change in position, while velocity measures an objects change in position per unit time.

Explanation:

Define speed and velocity

$$ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \quad (\text{Scalar quantity, magnitude only}) $$

$$ \vec{v} = \frac{\Delta \vec{x}}{\Delta t} \quad (\text{Vector quantity, magnitude and direction}) $$

Evaluate the given options

• Option A states that velocity measures rate and direction, while speed measures rate only. This matches the definitions of vector and scalar quantities.
• Option B is incorrect because velocity does not depend solely on speed; it also depends on direction.
• Option C is incorrect because velocity measures change in position per unit time (displacement), not change in speed.
• Option D is incorrect because both measure change in position per unit time, but velocity includes direction.

Answer:

• (A) Velocity measures an object's rate and direction of motion, and speed measures rate only. (Correct answer)
• (B) Velocity and speed both measure an object's change in position, but velocity only depends upon the object's speed.
• (C) Speed measures an object's change in position per unit time, while velocity measures an object's change in speed per unit time.
• (D) Speed measures an object's change in position, while velocity measures an object's change in position per unit time.