Physics 1301A/B Lecture Notes - Lecture 2: Negative Number, Quadratic Function

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carolinesnotes

18 Jun 2017

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Position and displacement: in one dimension, position can be described by a positive or negative number on a number line, also called a coordinate system. Position zero, the origin of the coordinate system, can be placed at any location: displacement is change in position. For motion along the x direction, displacement is designated x. Where x1 and x2 are the initial and nal positions, respectively. Average speed is the distance divided by time. Average velocity over a time interval t is de ned as the displacement divided by the time: for a round-trip, the average velocity is zero even though the average speed is not zero. Instantaneous velocity is the limit of the average velocity as the time interval becomes arbitrarily short. Velocity is the slope of the position-versus time curve. Instantaneous speed is the magnitude of the instantaneous velocity. Using calculus to find derivatives: in calculus, the derivative gives the result of the limiting procedure.

Related Questions

1. What is the difference between speed and velocity?

a. Speed is an average quantity while velocity is not.

b. Velocity contains information about the direction of motion while speed does not.

c. Speed is measured in mph, while velocity is measure in m/s.

d. The concept of speed applies only to objects that are neither. speeding up or slowing down, while velocity applies to every kind of motion.

e. Speed is used to measure how fast an object is moving in a straight line, while velocity is used for objects moving along curved paths.

2. The quantity 2.67 x 10³ has how many significant figures?

3. If Libby walks 100 m to the right, then 200 m to the left, her net displacement vector points

a. to the right.

b. to the left.

c. has zero length.

d. cannot tell without more information.

4. Velocity vectors point

a. in the same direction as displacement vectors.

b. in the opposite direction as displacement vectors.

c. perpendicular to displacement vectors.

d. in the same direction as acceleration vectors.

e. velocity is not represented by a vector.

chocolatemouse942

The figure shows three graphs, A, B, C, which collectively describe the motion of an object in one dimension. The horizontal axis of each graph is time (symbol t). The vertical axes of the graphs are different. For one graph the vertical axis is position (symbol x), for another, it is the velocity (symbol v), and for another, it is acceleration (symbol a). Where the axes across is the point of zero for both time and the quantity corresponding to the vertical axis. Part A: For which sequence of graphs is the vertical coordinate position, velocity, and acceleration, respectively? (e.g., If you think graph Y is position versus time, graph X is velocity versus time, and graph Z is acceleration versus time, then your answer is Y, X, Z.). Multiple choice: 1)C, A, B 2)A, C, B 3)C, B, A 4)B, C, A 5)B, A, C 6)A, B, C. Part (b) Which one of the following situations can be most accurately represented by the graph, consistent with your answer to part (a)? (1) A car driving in the negative x-direction suddenly shifts into reverse and, with tires spinning, slows to a momentary stop before beginning to move in the position x-direction. (2)A car driving in the position x-direction slams on its brakes and comes to rest. (3) A rock is dropped from the rest from the top of a tall building. Assume air drag can be neglected, in which case its speed increases by the same amount each second. Take upward to be the position x-direction. (4) A sprinter runs a 100-meter dash and she runs in the negative x-direction. Starting from rest, she has a constant acceleration for the first 50 meters, then a constant speed for the remaining 50. Multiple choices: 1)4, 2)3, 3)2, 4)1.

carmineporpoise991

While working on her bike, Amanita turns it upsidedown and gives the front wheel a counterclockwise spin. It spins atapproximately constant speed for a few seconds. During this portionof the motion, she records the x and y positionsand velocities, as well as the angular position and angularvelocity, for the point on the rim designated by the yellow-orangedot in the figure. (Intro 1 figure) Let theorigin of the coordinate system be at the center of the wheel, thepositive x direction to the right, the positive yposition up, and the positive angular position counterclockwise.The graphs (Intro 2 figure) begin when thepoint is at the indicated position. One graph may be the correctanswer to more than one part.

Intro 1

Intro 2

1. Which of the graphs corresponds to xposition versus time?

2. Which of the graphs corresponds to angularposition versus time?

3. Which of the graphs corresponds to yvelocity versus time?

4. Which of the following graphs corresponds toangular velocity versus time?

Physics 1301A/B Lecture Notes - Lecture 2: Negative Number, Quadratic Function

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