Introduction to One-Dimensional Motion

Key Terms Scalar Quantity Vector Quantity Distance Displacement Speed Take a minute and give your definition of the these key terms. Scalar Quantity Vector Quantity Distance Displacement Speed Velocity Acceleration

Quantities associated with motion Scalar Quantities do not have direction. Scalar quantities only have magnitude (how much) Ex: 15 meters, 28 km/s Vector Quantities have both magnitude and direction. Ex: 15 meters to the right, 28 km/s to the North

What’s the difference between distance and displacement? Distance: the total magnitude traveled For example, if you have to take the long way around a traffic jam, your distance increases Displacement: the shortest distance from the starting point to the ending point

The differences between distance and displacement The differences between distance and displacement can be summarized as: Distance Displacement Depends on the path Independent of path taken Always positive Can be positive or negative Is a scalar Is a vector

What is average speed?  

What is Average Velocity?  

Speed & Velocity Examples Speed is distance divided by time 2 cm/s Velocity includes the direction 2 cm/s west West

The differences between speed and velocity can be summarized as: Depends on the path taken Always positive (+) Is a scalar No dependence on direction and so is only positive Velocity Independent of path taken Can be positive (+) or negative (-) Is a vector Direction can be guessed from the sign (i.e., positive or negative)

What is the difference between average velocity and instantaneous velocity? Average Velocity: Total Displacement divided by total time Instantaneous Velocity: Velocity at a certain moment Ex: A school bus takes 45 minutes to travel 25 miles. What is the average velocity? What is the instantaneous velocity when it stops?

Using Graphs to Calculate Speed