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## High school physics

### Course: High school physics>Unit 1

Lesson 3: Average velocity and average speed

# Average velocity and speed review

How to calculate average velocity and speed in one-dimension in word problems

## Equations

EquationSymbol breakdownMeaning in words
v, with, \bar, on top, equals, start fraction, delta, x, divided by, delta, t, end fractionv, with, \bar, on top is average velocity, delta, x is displacement, and delta, t is change in time.Average velocity is displacement divided by time interval of the displacement.
v, start subscript, start text, a, v, g, end text, end subscript, equals, start fraction, d, divided by, delta, t, end fractionv, start subscript, start text, a, v, g, end text, end subscript is average speed, d is distance, and delta, t is change in time.Average speed is distance divided by time interval for the distance traveled.

## Common mistakes and misconceptions

• Average speed does not have to equal the magnitude of the average velocity. People may think that average speed and average velocity are just different names for the same quantity, but average speed depends on distance and average velocity depends on displacement. If an object changes direction in its journey, then the average speed will be greater than the magnitude of the average velocity.
• Speed is a scalar, and average velocity is a vector. Average velocity indicates direction and can be represented as a negative number when the displacement is in the negative direction. Average speed does not indicate direction and can only be positive or zero.