8.18 Velocity, Displacement, and Graphs

A set of practice flashcards covering average velocity, position-time and velocity-time graphs, area and slope relationships, and how to determine instantaneous velocity and acceleration.

What does the average velocity depend on?

Displacement over the total time; it depends on how far you went and how long it took, not on whether you were moving the whole time.

From a position-versus-time graph, what two things can you read?

Position at any given time, and the velocity obtained from the slope of the graph.

From a velocity-versus-time graph, what can you read?

Velocity at a given time; the displacement is given by the area under the curve; acceleration is given by the slope.

What does the area under a velocity-versus-time graph represent?

Displacement (change in position) over the time interval.

What does the slope of a velocity-versus-time graph represent?

Acceleration (change in velocity over time).

What does the slope of a position-versus-time graph give you?

Velocity at that time.

If a position-versus-time graph has a constant slope, what does that imply about motion?

The object is moving with a constant velocity.

If velocity is constant, what is the acceleration?

Zero (the velocity is not changing).

How do you compute delta v?

Delta v = vfinal − vinitial; calculated by subtracting the initial velocity from the final velocity.

What is acceleration?

Change in velocity over change in time; has magnitude and direction (sign).

How do you determine instantaneous velocity from a position-time graph?

Take the slope of the tangent at the desired time (or approximate with a small interval).

How do you determine instantaneous velocity from a velocity-time graph?

Read the velocity value at that time on the graph (the y-value).

What is the relationship between displacement, average velocity, and time?

Displacement Δx = v_avg × Δt.

How is average velocity different from instantaneous velocity in a trip with stops?

Average velocity depends on total displacement and total time; it does not require constant speed throughout the trip.

In one-dimensional motion, how do you determine the direction of acceleration?

Acceleration points in the direction of the change in velocity; speeding up in the same direction as motion, slowing down in the opposite.

What is a turnaround point on a velocity-time graph?

The time when velocity crosses zero, indicating a change in direction.