Describing Motion Vocabulary Displacement Distance Position Scalars Slope Vectors Uniform motion Position-time graph

I wonder... What descriptions of motion come to mind before, during and after the actions in the following photos?

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What questions arise from the following photos? I wonder... What questions arise from the following photos? (Q’s only please!)

8.1 Motion Many words are used when describing motion. Many of these words have specific meanings in science. Some common words used to describe motion include: Distance Time Speed Position Displacement Describe the motion of the soccer ball before and after it is kicked. What key words did you use when describing this situation?

Direction Makes a Difference: SCALARS AND VECTORS Magnitude refers to the size or amount of a measurement. Measurements that have only magnitude are called scalar quantities or scalars Eg. Time (5 min has no direction) Eg. Distance 5 km Eg. Speed 5 km/sec

VECTORS Example: 5 km north Vectors are quantities that have magnitude and direction (displacement, velocity, acceleration) Example: 5 km north Every time you use a map or give directions, you are using vectors.

(c) 2 hours driving in a car (d) swimming for 100 m [N] (e) 21°C Quick Check 1. Identify each of the following quantities as either vector or scalar. (a) 80 kg (b) 30 km [S] (c) 2 hours driving in a car (d) swimming for 100 m [N] (e) 21°C Scalar Vector Scalor scalar

DISTANCE Distance (d) is a scalar quantity that describes the length of a path between two points or locations. Example: A car traveled a distance of 10 km to the store

Example: The school is 3 km east of my house POSITION Position ( d ) is a vector quantity that describes a specific point relative to a reference point. Example: The school is 3 km east of my house The SI unit for both distance and position is metres (m).

DISPLACEMENT(∆d) Displacement describes the straight-line distance and direction from one point to another. It describes how much an object’s position has changed. The SI unit for displacement is metres (m). Between 2 s and 5 s the skateboarder’s displacement is 5 m [E]. The skateboarder’s distance travelled is 5 m.

The skateboarder’s displacement is 5 m [E]. Ex: What is the Skateboarder's displacement between 2 s and 5 s? Δd = 7m - 2m = 5m [E] The skateboarder’s displacement is 5 m [E].

Ex 2: If car leaves home and drives 10 km East to the store and then returns home. a) What is the total distance the car travelled? b) What is the total displacement?

a) What is the total distance the car travelled? Ex 2:If car leaves home and drives 10 km East to the store and then returns home. a) What is the total distance the car travelled? b) What is the total displacement? The car has driven a total distance of 20 km Displacement is 0 km

Time Interval(Δt) Time (t) is a concept that describes when an event occurs. Initial time (ti) is when the event began. Final time (tf) is when the event finished. Time interval is the difference between the final and initial times. Time interval is calculated by:

Ex: 1. What is the position of the sign relative to the tree? 2. What is the time interval to move from the fire hydrant to the sign?

Ex: 1. What is the position of the sign relative to the tree? The position of the sign is 7 m east of the tree 2. What is the time interval to move from the fire hydrant to the sign?

Watch for Signs When using vector quantities, opposite directions are given opposite signs. North, east, up, and right are called positive (+). South, west, down, and left are called negative (–). Common sign conventions

Ex 3: What is the person’s displacement between 0 s and 15 s . Ex 4: What distance did the person walk in this same time interval?

Ex 3: What is the person’s displacement between 0s and 15s? = 10 m [W] – 5 m [E] = -10 m – 5 m = -15 m = 15 m [W] Ex 4: What distance did the person walk in this time interval? 20+20+10 =50 m

In class 8-1B p352

Homework Work book p147-149 Checking Concepts p 361 # 1-10