Vocabulary Select the correct term to complete the sentences. Position Average speed Graph Independent variable Dependent variable Acceleration due to gravity Projectile Speed Velocity Coordinates Constant speed Acceleration Origin Vector Axis Slope Free fall 1. Speed with direction is called ____. 2. A variable that is described using both a number and a Direction is called a ____. 3. The ____ is the place where position equals zero. 4. The ____ of an object is given relative to an origin. 5. The formula for ____ is distance divided by time. 6. ____ is speed that does not change over time and ____ is the Total distance divided by the total time of a trip. 7. The ____ of the origin of a graph are (0, 0). 8. The x-____ is horizontal on a graph. 9. A mathematical diagram using two axes to represent the Relationship between variables is a(n) ____. 10. The ____ of a line is the ratio of rise to run. 11. The variable usually represented on the x-axis of a graph is the ____. 12. The variable usually represented on the y-axis of a graph is the ____. 13. The rate at which velocity changes is defined as ____. 14. An object moving in a curved path and affected only by gravity is called a(n) ____. 15. An object accelerating under only the force of gravity is said to be in ____. 16. An object in free fall will accelerate toward Earth at 9.8 m/s2, the ____. Concepts 1. What is the speed of an object that is standing still? 2. Name three common units for measuring speed. 3. Write the form of the speed equation that you would see in each of the following scenarios. Let v = speed, t = time, and d = distance. a. You know distance and speed and want to find the time. b. You know time and distance and want to find the speed. c. You know speed and time and want to find the distance. 5. Are the following directions usually are considered positive or negative? Write + for positive or − for negative. a. ____ up e.____ north b. ____ down f.____ south c. ____ left g.____ east d. ____ right h.____ west 6. If you are given x-y axes coordinates of (4, 9), which axis is represented by the number 9? 7. You do an experiment to find out how much light is needed to make house plants grow taller. The two variables in this experiment are amount of light and the height of the plants. Which variable is the dependent variable and which is the independent variable? 3. Lance Armstrong’s teammate, George Hincapie, averaged a speed of 33.6 km/h in the 15th stage of the Tour de France, which took 4.00 hours. How far (in kilometers) did he travel in the race? 4. It takes Brooke 10 minutes to run 1 mile. What is her speed in miles per minute? 5. You are traveling on the interstate highway at a speed of 65 mph. What is your speed in km/h? The conversion factor is: 1.0 mph = 1.6 km/h. 21. When a ball is first dropped off a cliff in free fall, it has an acceleration of 9.8 m/s2. What is its acceleration as it gets closer to the ground? Assume no air friction. 22. Why is the position vs. time graph for an object in free fall a curve? 23. Draw a speed vs. time graph for an object accelerating from rest at 2 m/s2. 24. Draw a speed vs. time graph for a car that starts at rest and steadily accelerates until it is moving at 40 m/s after 20 seconds. Then answer the following questions. a. What is the car’s acceleration? b. What distance did the car travel during the 20 seconds? 25. Draw a speed vs. time graph for each of the following situations. a. A person walks along a trail at a constant speed. b. A ball is rolling up a hill and gradually slows down. 3. Answer the following questions. a. A herd of wild animals moves in the following directions from a starting point in search of water: 10 km north, 3 km east, 7 km west, 20 km south, and 4 km east. Where does the herd end up relative to its starting point? b. A watering hole is 2 km west and 2 km south of the starting point. Does the herd make it to the watering hole? 2. Suppose you are moving left (negative) with a velocity of -10 m/s. What happens to your speed if you have a negative acceleration? Do you speed up or slow down? 9. A ball is in free fall after being dropped. What will the speed of the ball be after 2 seconds of free fall? 10. What happens when velocity and acceleration are not in the same direction? What kind of motion occurs? 1. On a graph of position vs. time, what do the x-values represent? What do the y-values represent? 2. Explain why time is an independent variable and position is a dependent variable in a position versus time graph. 3. What does the slope of the line on a position vs. time graph tell you about an object’s speed? 1. What is the difference between distance and position? 2. From an origin you walk 3 meters east, 7 meters west, and then 6 meters east. Where are you now relative to the origin? 3. What is your average speed if you walk 2 kilometers in 20 minutes? 4. Give an example where instantaneous speed is different from average speed. 5. A weather report says winds blow at 5 km/h from the northeast. Is this description of the wind a speed or velocity? Explain your answer. 6. What velocity vector will move you 200 miles east in 4 hours traveling at a constant speed? Distance Time Speed Abbreviation Meters m/s Hours Kilometers per hour Seconds Centimeters per second Miles Hours mph Distance Speed Time 10 6 45 5 100 2