AP Physics C/Motion in One Dimension
Scalars vs. Vectors
[edit | edit source]- Scalars
- measurements that have no direction to them
- Examples: Distance, speed
- Vectors
- measurements that have a direction to them
- Examples: displacement, velocity
Displacement vs. Distance
[edit | edit source]Displacement - the most direct route from one point to another. (The net distance traveled)
Distance- the length traveled
Example Problem:
If a car travels 3m directly east then 5m directly west, what is the displacement and what is the distance traveled?
Displacement: if a car goes 3m east, and then it goes 5m opposite of east, the car will travel enough to cancel out the 3m east traveled, and go an extra 2m after that. This is best represented in an equation:
If east is positive:
=3m (east) + 5m (opp. east)
=3m (east) + (-5)m east
= -2m east
= 2m west
Displacement is often represented by the variable s, or x.
Velocity vs. Speed
[edit | edit source]Speed- change in distance over change in time
Velocity- the change in displacement divided by the change in time. It is also defined as the derivative of the displacement equation. Velocity is a vector.