Scalars vs Vectors
A quantity that has magnitude only.
What is a scalar?
The total length of the path traveled.
What is distance?
The rate of distance traveled.
What is Speed?
A change in velocity over time.
What is acceleration?
What does the slope of a position vs time graph represent?
Velocity.
A quantity with both a magnitude and a direction.
What is a vector?
A straight-line change in position from start to finish.
What is displacement?
The rate of change of position including direction.
What is velocity?
What does negative acceleration mean?
The object is slowing down.
What does a flat line on a position vs time graph mean?
The object has stopped.
Speed is a _____ quantity.
Scalar.
A car drives 8m east, then 6m west - what is the distance and displacement?
Distance = 14m; Displacement = 2m east.
A runner travels 100m east in 20 s - find the average speed and velocity.
velocity = 5m/s east
A car goes from 5m/s to 15m/s in 2s- find acceleration..
a = 5m/s^2
What does the slope of a velocity vs time graph represent?
Acceleration.
Acceleration is a _____ quantity.
Vector.
Can displacement ever be greater than distance?
No, distance is always greater than or equal to displacement. Displacement is the shortest path.
Explain how an object can have constant speed but changing velocity.
If it changes direction.
A bike slows from 12m/s to 4m/s in 4s - find acceleration.
a = -2m/s^2
What does the area under a velocity vs time graph represent?
Displacement.
Why is displacement a vector but distance is a scalar?
Displacement includes direction and can be positive/negative; distance only measures total path length.
An object goes from x = 0 --> +5 --> -2 on a position vs time graph. What is the Displacement and distance?
Distance = 5 + 7 = 12m
Displacement = -2m
Can an object's average speed be nonzero while it's velocity is zero?
Yes, if the object returned to the start (net Displacement = 0)
How can you tell an object is accelerating on a velocity vs time graph?
The slope is not zero (slanted, not flat)
Describe the motion story of a graph where the position rises, then flattens, then decreases over time.
The object moves forward, stops, then goes back.