Position, Speed, and Velocity

What is position?

The location of an object relative to a reference point.

What is velocity?

The rate of change of position over time.

What is speed?

The rate of distance traveled over time.

What quantities have magnitude and direction?

Vector quantities.

Is velocity a vector or scalar?

Vector.

Is speed a vector or scalar?

Scalar.

Why is speed scalar?

Because it has magnitude only and no direction.

Formula for velocity?

v = Δx / Δt

Formula for change in position?

Δx = xf - xi

Formula for speed?

speed = distance / time

What does a negative velocity mean?

Motion in the negative direction (usually left/down).

What does positive velocity mean?

Motion in the positive direction (usually right/up).

Does distance include direction?

No.

Does displacement include direction?

Yes.

If an object returns to its starting point, what is displacement?

Zero.

If an object returns to its starting point, is distance zero?

No.

What is a vector quantity?

A quantity with both magnitude and direction.

What is a scalar quantity?

A quantity with magnitude only.

Why is position a vector quantity?

Because it requires both magnitude and direction.

What does Δx represent?

Change in position (displacement).

How do you calculate displacement?

Final position minus initial position.

What is the SI unit for velocity?

Meters per second (m/s).

What is the SI unit for speed?

Meters per second (m/s).

What is the SI unit for position?

Meters (m).

What does positive position usually mean?

The object is to the right or above the origin.

What does negative position usually mean?

The object is to the left or below the origin.

Does velocity depend on direction?

Yes.

Does speed depend on direction?

No.

What is displacement?

The straight-line change in position from start to finish.

What is distance?

The total path traveled.

What happens to displacement in a round trip?

Displacement becomes zero.

What happens to distance in a round trip?

Distance is still greater than zero.

What does average velocity measure?

Total displacement divided by total time.

What does average speed measure?

Total distance divided by total time.

Why can velocity be negative?

Because it includes direction.

Can speed ever be negative?

No.

What does a velocity of +5 m/s mean?

The object moves 5 meters to the right every second.

What does a velocity of -4 m/s mean?

The object moves 4 meters to the left every second.

What is a reference frame?

The coordinate system or origin used to measure position.

Why does position depend on the reference frame?

Changing the origin changes the measured position.

What is the standard positive direction on a horizontal axis?

Right.

What is the standard positive direction on a vertical axis?

Up.