2 Distance and Displacement Chapter 11 Section 1Pg
3 Distance and Displacement To describe_________ , you must state the direction the object is moving as well as how fast the object is moving. You must also tell its ________ at a certain time.
4 Choosing a Frame of Reference ________________: a system of objects that are not moving with respect to one another; it is the necessary ingredient of a description of motionMust answer these 2 questions…___ fast are you moving?Which _____ should you choose?
5 Choosing a Frame of Reference How fast are you moving?Relative motion: movement in ________ to a frame of referenceExample: as a train moves past a platform, people standing on the platform will see those on the train speeding by. But when the people on the train look at one another, they don’t seem to be moving at all.
6 Choosing a Frame of Reference Which frame should you choose?Example: If on a train, looking at a treetop will help you see how fast you are moving relative to the ground. If you are walking on the train, then looking at a seat will help you see how fast you are moving relative to the train.
7 Measuring Distance Distance: the ______ of a path between two points. SI unit of measure= meter (m)For very long distances, _________ (km) is used1 km = 1,000 mSmall distances, __________ (cm)
8 Measuring Displacements ______________ provides this information:Distance is the length of the path between two points.Displacement is the ________ from the starting point and the length of a straight line from the starting point to the ending point.Displacement is sometimes used when giving directions.
9 Combining Displacements Displacement is an example of a ______.Vector: a quantity that has magnitude and direction_________ can be size, length, or amountRepresented on a map by arrowsThe length of the arrow shows the magnitude of the vector.Vector _______ is the combining of vector magnitudes and directions. Add displacements using vector addition.
10 Combining Displacements Displacement Along a Straight LineWhen 2 displacements, represented by two vectors, have the _______ direction, you can _____ their magnitudesWhen 2 displacements have the ________ direction, you can _________ their magnitudes
11 Combining Displacements Displacement That Isn’t Along a Straight PathWhen 2 or more displacement vectors have ________ directions, they may be combined by graphing.See Figure 4 on page 331______________: (vector in red) the vector sum of two or more vectors
13 Speed_____: the ratio of the distance an object moves to the amount of time the object moves.SI unit= meters per second (m/s)However, choose units that make the most sense for the motion you are describing2 ways to express the ______ of an object are average speed (computed for the entire duration of a trip) and instantaneous speed (measured at a particular instant)
14 SpeedAverage Speed____________, ν, is the total distance traveled, d, divided by the time, t, it takes to travel that ________
16 Speed Instantaneous Speed How ___ you are going at a particular moment This is what your car’s speedometer gives you____________ speed, ν, is the rate at which an object is moving at a given moment in time
17 Graphing MotionTo describe _______- a distance-time graph should be usedThe _____ of a line on a distance-time graph is speed.Slope of straight portions represent periods of constant speed______ represent a gradual increase or decrease in speedSteeper slope means a ______ speedSee page 334 in book
18 VelocityTogether, the speed and direction in which an object is moving are called ________Velocity is a description of both speed and direction of motion.Velocity is a ______.Longer vector represents a faster speedShorter vector represents a slower speedUniform motion is another way of saying constant velocityA ______ in velocity can be the result of a change in speed, a change in direction, or both
19 Combining Velocities Two or more velocities add by vector addition See page 337, Figure 10 in book
21 What is Acceleration? ____________: the rate at which velocity changes Acceleration can be described as changes in speed, changes in direction, or changes in bothAcceleration is a ______
22 What is Acceleration? Changes in Speed Acceleration is often used to describe situations in which the _____ of an object is ________.Scientifically, acceleration applies to any change in an object’s _______. The change may be either and increase (positive) or a decrease (negative) in speed
23 What is Acceleration? See example in your book Page 343 (2nd paragraph, also figure 12)An example of acceleration due to a change in speed is __________The movement of an object toward Earth solely because of _______.Units are meters per second squared (m/s2)Objects falling near Earth’s _______ accelerate downward at a rate of 9.8 m/s2
24 What is Acceleration? Changes in Direction Acceleration may still occur when speed is __________.Example: you experience acceleration when you ride your bicycle around a curveEven if you have constant ______, change in direction means you are accelerating.
25 What is Acceleration? Changes in Speed and Direction _______ is characterized by both changes in speed and direction at the ____ timeThink about a ride on a roller coaster…Acceleration isconstantly ________because of changes inthe speed and directionof the cars on the rollercoaster.
26 What is Acceleration? Constant Acceleration Constant Acceleration- a steady ______ in velocityThe velocity of an object moving in a _______ ______ changes at a constant rate when the object is experiencing constant acceleration
27 Calculating Acceleration Acceleration for straight-line motiona= change in velocity ortotal timeVelocity ________: acceleration will be negativeVelocity increases: acceleration will be _______
28 Calculating Acceleration See worked example on page 346Work problems 1-4 on page 346
29 Graphs of Accelerated Motion ______ can be used to calculate accelerationThe slope of a speed-time graph is acceleration
30 Graphs of Accelerated Motion Speed-Time GraphsConstant _________ is represented on a speed-time graph by a straight lineLinear graph- displayed data form straight-line parts; the ______ is accelerationSee example graphsPg. 347
31 Graphs of Accelerated Motion Distance-Time GraphAccelerated motion is represented by a _____ line on a distance-time graph(example: pg. 348)Nonlinear graph- a curve connects the data points that are ______Increasing slope = increasing ______
32 Instantaneous Acceleration Acceleration is ______ constantMotion is rarely in a straight lineInstantaneous __________ is how fast a velocity is changing at a specific instant.Remember: acceleration involves a change in velocity or direction or _____
33 Works CitedFrank, Wysession, & Yancopoulos. “Chapter 11 Motion.” Physical Concepts in Action. Upper Saddle River: Pearson, Print.