 # 11.2 Speed and Velocity Slow versus fast movement can be described in terms of ___________ The speed of an in-line skater is usually described in ________.

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11.2 Speed and Velocity Slow versus fast movement can be described in terms of ___________ The speed of an in-line skater is usually described in ________ The speed of a car is usually described in ___________. speed m/s km/h

11.2 Speed and Velocity Key Concepts How are instantaneous speed and average speed different? How can you find the speed from a distance-time graph? How are speed and velocity different? How do velocities add?

11.2 Speed and Velocity Speed Speed is the ratio of the _____________ an object moves to the amount of _____________ the object moves. SI unit = meters per second ________. Average speed is computed for the _________ duration of a trip Instantaneous speed is measured at a particular _____________. distance time m/s entire instant

11.2 Speed and Velocity Calculating Average Speed _______ While traveling on vacation, you measure the times and distances traveled. You travel 35 kilometers in 0.4 hour. v 35 km.4 h = 87.5 km/h

11.2 Speed and Velocity 2. A train travels 190 kilometers in 3.0 hours, and then 120 kilometers in 2.0 hours. What is its average speed? Total distance = Total time = Speed 190 km + 120 km= 310 km 3.0 h + 2.0 h 310 km = 5 h 5 h = 62 km/h

11.2 Speed and Velocity Instantaneous Speed ____ Sometimes you need to know how fast you are going at a particular moment. The speedometer in a car measures the car’s instantaneous speed Notice the scale marking are given both in _______ and _______ v km/h mph

11.2 Speed and Velocity Graphing Motion The ________ of a line on a distance-time graph is speed. Use a point on the graph to determine speed… _d_ t slope = ______ 100 m 4 s 25 m/s

11.2 Speed and Velocity A steeper slope on a distance-time graph indicates a _____________ speed. faster

11.2 Speed and Velocity Velocity Velocity is a description of both _____________ and ____________ of motion. Velocity is a ____________. To describe the velocity of a cheetah correctly, you must assess it’s speed and many directional changes speed direction vector

11.2 Speed and Velocity As the sailboat’s direction changes, its velocity also ______________, even if its speed stays the same. Since velocity is a vector, It can be represented __________ Velocity changes arrows

11.2 Speed and Velocity Combining Velocities Two or more velocities add by ___________ ________________. Ex: If a boat is moving on a flowing river, you must calculate the velocity of the ______________ relative to the riverbank and the velocity of the ______________ relative to the river. Combined, they yield the velocity of the boat relative to the riverbank. 5 km/h + 12 km/h = vector addition river boat 17 km/h

11.2 Speed and Velocity The resultant velocity shown is a combination of the current _______ and the velocity of the ____________ relative to the river The _______________ resultant velocity is… Combining Velocities (x) boat (y) measured (z) 13 km/h

11.2 Speed and Velocity You can also calculate the resultant velocity with the Pythagorean theorem formula… x 2 + y 2 = z 2 5 2 + 12 2 = z 2 25 + 144 = z 2 169 = z 2 Combining Velocities 13 = z

11.2 Speed and Velocity Assessment Questions 1.A woman jogs 10 kilometers in one hour, stops at a restaurant for one hour, and then walks 10 kilometers in two hours. What is her average speed for the outing? a.0.2 km/h b.4 km/h _10 km + 10 km_ c.5 km/h 1h + 1h + 2h d.10 km/h

11.2 Speed and Velocity Assessment Questions 2.Lisa plotted time on the x-axis of a line graph and distance on the y-axis. What does the slope of her graph represent? a.total distance traveled b.velocity c.speed d.displacement

11.2 Speed and Velocity Assessment Questions 3. A kayak is moving across a stream that is flowing downstream at a velocity of 4 km/h. The kayak’s velocity is 3 km/h. What is the magnitude of the kayak’s velocity relative to the river bank? a.1.3 km/h b.5 km/h c.7 km/h d.12 km/h 4 km/h 3 km/h 3 2 + 4 2 = z 2 9 + 16 = z 2 25 = z 2

11.2 Speed and Velocity Assessment Questions 4. The SI unit for speed of an airplane is miles per hour. True False

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