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Motion Review Displacement, Vectors, Frame of Reference, DistanceTime Graphs, Speed, Velocity, Acceleration The SI unit for speed is a.mph. c.m/s. b.ft/s2. d.Dv / t. On a velocity-time graph, a line with a negative slope indicates that the object is a.speeding up. c.not moving. b.slowing down. d.traveling at a constant speed. An object that changes position relative to a reference point is a.stationary. c.moving at constant speed. b.in motion. d.moving at constant velocity. Average speed can be represented by the mathematical expression a.distance/time. c.time – distance. b.distance ´ time. d.time + distance. The _____ of an object consists of its speed and direction. a.velocity c.average speed b.instantaneous speed d.displacement The average speed of a runner who runs 500.0 m in 1.6 min is a.0.19 m/s. c.96 m/s. b.5.2 m/s. d.312 m/s. 60 sec. = 1 min. The average speed of a runner who runs 500.0 m in 1.6 min is a.0.19 m/s. c.96 m/s. b.5.2 m/s. d.312 m/s. 60 sec. = 1 min. A car moving at an average speed of 55.0 mi/h for 4.25 h has traveled distance a.0.08 mi. c.55 mi. b.13 mi. d.234 mi. Time Velocity A car moving at an average speed of 55.0 mi/h for 4.25 h has traveled a.0.08 mi. c.55 mi. b.13 mi. d.234 mi. On a distance vs. time graph of an object’s motion, distance is usually a.plotted on the x-axis. c.the dependent variable. b.greater than time. d.measured in ft/min. A pitcher throws a baseball to home plate, a distance of 60.5 ft. The ball reaches home plate in 0.63 s. What is the velocity of the ball? a.38 ft/s c.96 ft/s b.38 ft/s toward home plate d.96 ft/s toward home plate A pitcher throws a baseball to home plate, a distance of 60.5 ft. The ball reaches home plate in 0.63 s. What is the velocity of the ball? a.38 ft/s c.96 ft/s b.38 ft/s toward home plate d.96 ft/s toward home plate When the motion of an object is shown by a straight line on a distance vs. time graph with distance on the y-axis, the slope of the line is the a.distance traveled. c.speed. b.displacement. d.time of travel. Displacement must always indicate a.velocity. c.speed. b.direction. d.time. Speeding up, slowing down, and changing direction is best described as a.velocity. c.displacement. b.distance. d.acceleration. The equation for finding average acceleration for straightline motion is a.initial velocity – final velocity ´ time. b.final velocity – initial velocity/time. c.initial velocity + final velocity + time. d.initial velocity + final velocity – time. Moving from 0 m/s to 25 m/s in 8.0 s equals an average acceleration of a.0.32 m/s. c.3.1 m/s. b.0.32 m/s2. d.3.1 m/s2. Moving from 0 m/s to 25 m/s in 8.0 s equals an average acceleration of a.0.32 m/s. c.3.1 m/s. b.0.32 m/s2. d.3.1 m/s2. A cyclist is traveling from an initial speed of 10.0 m/s to a final speed of 14.5 m/s. What is her acceleration after 9.0 s? A.0.5 m/s The change in Velocity C.45 m/s B.0.5 m/s2 Time acceleration D.45 m/s2 A cyclist is traveling from an initial speed of 10.0 m/s to a final speed of 14.5 m/s. What is her acceleration after 9.0 s? A.0.5 m/s C.45 m/s B.0.5 m/s2 D.45 m/s2 Peter runs in a constant direction on a straight road. The velocity vs. time graph of Peter’s motion shows a straight line with a negative slope. What does the line tell you about Peter’s speed? a.It is increasing. c.It is decreasing, then increasing. b.It is decreasing. d.It is constant. When velocity changes by the same amount over each time interval, acceleration is a.zero. c.positive. b.constant. d.negative. On a velocity vs. time graph, what shows the value of the acceleration? a.the slope of the line c.the y-axis b.the x-axis d.the final velocity A cheetah can accelerate at up to 6.0 m/s2. How long does it take for a cheetah to speed up from 10.5 m/s to 12.2 m/s? a.0.28 s c.3.5 s b.1.7 s d.10 s A cheetah can accelerate at up to 6.0 m/s2. How long does it take for a cheetah to speed up from 10.5 m/s to 12.2 m/s? a.0.28 s c.3.5 s b.1.7 s d.10 s The distance traveled by an object divided by the time it takes to travel that distance is called a.average velocity. c.average acceleration. b.average speed. d.negative acceleration. On a distance vs. time graph, the line of an object at rest is a a.curved line with a slope of zero. c.jagged line with a negative slope. b.flat line with a slope of zero. d.curved line with a positive slope. The difference between speed and velocity is that velocity includes a.direction. c.time. b.distance. d.weight. In order to determine speed, you must know a.only time. c.both time and distance. b.only distance. d.neither time nor distance. When an object slows down, its acceleration is a.positive. c.negative. b.centripetal. d.constant. Displacement a.must be in a particular direction. b.is the change in position of an object. c.must be a straight line. d.All of the above On a speed vs. time graph, constant acceleration is represented by a a.straight line. c.jagged line. b.slightly sloped line. d.steeply sloped line. At which of the following points on the above graph is the speed the greatest? a.Point 1 c.Point b.Point 2 d.Point 4 At which of the points on the graph above is the object at rest? a.Point 1 c.Point 3 b.Point 2 d.Point 4 One of these is NOT a unit of distance. Which one? a.Mile c.Newton b.Inch d.Meter . Match the position vs. time graph with the correct speed vs. time graph. A B C In the equation “S = ΔD/ΔT”. The “/” means: a.addition c.multiplication b.subtraction d.division Vi Vf m/s Δ Means “change of” and equal final - initial. the starting speed. Equals zero for an object that begins at rest. units for velocity Equals zero for an object that is stopping. Acceleration Linear speed slope independent variable How far something moves in a certain amount of time and the slope of a position vs. time graph. A graph that looks like a straight line. A variable that is not dependent on the other (on the x-axis). The rate of change in the speed of an object (how fast something changes speed). A measurement of how steep a line is. Speed or Velocity? a)A person walking 2 mph north. velocity b) A bird flies 20 m/s. Speed Are these are accelerating (yes or no)? a) At constant velocity? no B) Going 20 m/s around a corner? yes C) Stopping from 20 m/s. yes D) An object at rest. no An object is accelerating at 10 m/s2. If the object starts at rest: a) How fast is it going after 1 second? 10 m/s b) How fast will it be going after 3 seconds? 30 m/s An object is traveling 3 m/s. a) How far does it travel each second? 3m B) How far will it go in 3 seconds? 9m Car A is going 12 m/s. Car B is going 20 m/s. a)Which car travels more distance each second? B b)Which car reaches 50 m last? A Which car goes 100 m? Both Acceleration Acceleration is the rate of change of velocity Velocity is speed with direction. Changing your direction means you are accelerating. Analyzing Graphs http://www.zimbop.com/physics/R%20Analyzing%20M otion%20Graphs%20with%20numbers.pdf Positive Velocity Zero Acceleration Positive Velocity Positive Acceleration How to Calculate the slope Slope ∆ = ∆ Displacement vs. Distance Be able to draw the vector. For example: Ray runs 30 feet north, 30 feet west, and then 30 feet south. What is his displacement in each direction? What is his total distance? Explain why displacement and distance are not the same. Position vs. Time Graph Basic Shapes of Velocity-Time Graphs Can you identify the motion by the shape of the graph? http://flightline.highline.edu/escott/courses/uwcrses/1 98/inv1wa/Image2.gif Comparing Graphs