X ot Topic:|madeacouple change: X @ 2sgHCHWCh2@N (hpdf X YA 28 HW Ch1(20)-Physics 280 X | /Desktop%%20user/Downloads/2ag%20HCHW%20Ch%202%20(31)%20(1).pdf - 9% + | @O 11 a. Put in two words: A train moves with one-dimesional motion. This means along the x-axis below the train can either move Ty ST 3iiHalis 6l -7 -6 -5 -4 -3 -2 b. Draw the postion and velocity vector for each train above. . How you draw the size of the velocity vector of each train is unrelated to the size of each position vector. Explain why. Give a short sentence as your answer. ANS: the position vectors have units of distance like meters but the velocity vectors. have units of distance over time like meters per second. 2.2. a. A dog is running. If its velocity vector component is v = 0.41: then which picture of the dog is correct if using the standard orientation of the axis (seen below) where postive is to the right. 32 0120l #1 , b. If its velocity vector component is v = DA? then which picture is correct if using the non- standard axis seen below where postive is now to the left. g AT a0 -2 ) #1 #2 c. If a physics student say: sacat's speedis [v] = 0.4 ? Explain in a short sentence why you don't Kknow If the cat is moving left or right. d. A dog moves with initial position x; = 2m with net displacement Ax = 5m. Draw the initial and final position vectors (arrows) of the dog below. HELP: recall that postion vectors are drawn with their tail at the origin and tip at the location of the object. The dog must have final postion x, = =7m T T T Tt Lolileiioniali=3iis2:s1 11001 21413 o search X w Topic | opic:l made a couple change: X @ 2ag HCHW Ch 2 (31) (1).pdf X Y\\ 2agHWCh 1(20) - Physics 230 X | # - t Jesktop%20user/Downloads/2ag%20HCHW%20Ch%202%20(3 1)%20(1).pdf e. Suppose a dog moved so that its initial postion was x = +1m and the magnitude of its displacement vector was |Ax| = 5m. Explain in a short setence why you don't know if the dog's final position is - 4m or + 6m. 33. a. The dog seen below moves with velocity v = 1.5 ? Put a number in the first blank and a word in the second: It's speed is m/s and its direction is . Assume the standard orientation of the axis where postive is the right. b. Suppose also that a cat moves with velocity v = =3.0 % Draw the velocity vector on each animal below and comment on the drawing scale: i.e., how much longer is the cat's velocity vector compared to the dogs? 4 A quick way to see if a variable n represents a vector component or a scalar is to add the phrase \"in the direction east\" and see if that sentence makes sense. Do that to each below and state if the variable represents a scalar or vector a. A force of F = 10 lbs was applied to the brick b. Juan drank V = 2 Liters of Pepsi. 5.C. 8 A 3} et 10 o 10 20 30 40 50 The jogger moves from point A to point B. Assume distance units of feet [ft] a. Onanaxes withno numbers you will often see like a +and/or = symbol at the end of the axis e X What purpose does the + sign serve? Explain ina short sentence. HELP: See problem 2.2a,b. b. In the diagram above, what is the jogger's initial position? c. What s the jogger's final position? d. What is his displacement? e. What distance did he move? , Draw both position vectors and the displacement vector in the picture above. WeLp: the displacement vector has its tail at the initial position and tip at the final position. ijcs.ume quantities in physics are not just numbers but are considered a geometric arrow (having both a size and direction). These quantities are called. Activate Wind i YR to search x 5 st Topic:imade s couple change: X @ 2agHCHWCh2@N) (Dhpdf X YR 2agHW Ch 1 (20) - Physics 2a s/Desktop%20user/Downloads/2ag%20HCHW620Ch%202%20(31)%20(1).pdf b. Physics quantities that are not arrows (i.e, don't have a direction) arecalled_______. . Classify each as a scalar (S) or vector V) (i) position (ii) displacement (iii) time (iv) distance (v) velocity (Vi) speed (vii) acceleration 7.C. a. When you add two vectors you get another vector: yes or no? b. When you subtract two vectors you get another vector: yes or no? o Given the coordinate system below where increasing numbers are to the right and decreasing numbers are to the left, any vector component that has a negative value must point left or right? >+ TR iiay g e i as s 4 S I S P IS S d. Ifavector has a positive component, then which way does it point for the axis above? e. The magnitude of a vector means its size. Size is always a positive. number. The magnitude of any one-dimensional vector can be found by taking its absolute value: yes, of no? ANS: yes. . Whatis the quick name given to the letter s. 8.6. . Draw the addition of the two force vectors on a separate sheet: this is called the net force or total force Faer = F1 + Fz. HELP: Use the tail-to-tip drawing rule \"the magnitude of the velocity vector\". HELP: it starts with F A > b. Suppose F, has size 6and F, has size 2. What s the size of Fid HELP: recall that the size of a vector is called its rmagnitude and s always a positive quantity. . Two momentum vectors are seen below. Draw Per = P1 +P20n3 separate sheet P2 d. Suppose Py hassize 8 and P, has size 4. Whatis the size (positive) of Prec? 9.6. a. Two position vectors are seen: Draw the displacement ; , ona separate sheet. %y *; b. Suppose has magnitude 6 andj, has magnitude 2. What is the magnitude of AX = % %y Activate Windows (R G L ere to search s 1216 AM e B 3/9/2024 D x | Topic: I made a couple changes x 2ag HCHW Ch 2 (31) (1).pdf * V 2ag HW Ch 1 (20) - Physics Zag 1+ X rs/Desktop%20user/Downloads/2ag%20HCHW%20Ch%202%20(31)%20(1).pdf a 5 / 14 - 90% +8 c. Two velocity vectors are seen. Draw the difference v2 - v1 . Suppose u, has magnitude 5 and uz has magnitude 10. What is the magnitude of Av ? 10.8. a. A car moves one-dimensionally. It starts at x = 15m then moves a distance of 200m to the right, then 100m left. Find the total distance moved and displacement of the car for the entire motion. As part of your work draw the path of the car and the following vectors: initial position, final position and displacement. ANS: 300, 100 b. A second car starts at -20m and drives 50m to the right in 4s then moves 80m left in 6s. Find its initial and final position, net displacement, total distance moved, average speed and average velocity. Indicate which are scalars(S) and which are vectors(V). Draw the object at the initial and final positions (ok to draw the car as a box0 and draw all vectors involved on the axis below. 10 30 20 10 6 10 20 30 40 11.C. Displacement Ax is often interpreted as a "directed distance". Explain what the difference is between "distance" and "directed distance". As a feel for what this question is asking, consider the two situations below for the initial and final positions of a moving object. #1. x1 = 3m, X2 = 7m #2. x1 = 7m, x2 = 3m 12.C. (a). Car #1 has position x = -40m and velocity v = 3-. Car #2 has position x = 10m with velocity v = -9" Draw the cars and the associated vectors below. 1 30 20 .10 0 10 20 30 40 meter Activate Windows Go to Settings to activate Windows 12:16 AM here to search 3/9/2024 SAMSUNGTopic: | made a couple changes x 2ag HCHW Ch 2 (31) (1).pdf x WA 2ag HW Ch 1 (20) - Physics Zag * + X s/Desktop%20user/Downloads/2ag%20HCHW%20Ch%202%20(31)%20(1).pdf 6 / 14 - 90% + | (b). How much longer should car #2's velocity be drawn compared to car #1? (c). Explain why you can't compare a position vector's size to a velocity vector's size. 13.C. Suppose remote-control toy car can move backward/forwards according to the equation = 2+3 - 5t2 where position is in [m] and time in [s] . True or false: the t variable in this equation is an "instant" of time and can be any real number like 0, 0.3s, 2s, 3.86s, or 11.774s. b. Compute the car's average velocity from 0s to 3s HELP: Vang Ax 14.E. Average velocity is always computed between two instants in time (called a time interval) whereas instantaneous velocity is always computed at one instant in time. We explore how these two (average versus instantaneous) are related below. Instantaneous velocity v: how is it different than average velocity Vang 1. Average velocity Vang is always computed between two times ty, t2 2. Instantaneous velocity v is the velocity at one instant in time t, and is approximately equal to the average velocity if the time interval At = t2 - ty is small. v(t1) Vavg when tz is close to t, approximately equal to In a physics experiment a toy car moves with position function x(t) = 0.15+3 function notation Fill out the two tables below (the first row is done for you already) time [s] position [m] Vavg from 1s to 5s 4.65 m/s 18.75 avg from 1s to 2s Vang from 1s to 1.5s 1.5 Wang from 1s to 1.1s 1.1 Wang from 1s to 1.015 1.01 Activate Windows Go to Settings to activate Windows. What is the best approximation to the car's instantaneous velocity at 1s? ANS: 0.45 CA 12:16 AM 3/9/2024 to search SAMSUNGProgram x | Topic: I made a couple changes * $ 2ag HCHW Ch 2 (31) (1).pdf * VA Zag HW Ch 1 (20) - Physics 2ag * |+ X File C:/Users/Desktop%20user/Downloads/2ag%20HCHW%20Ch%202%20(31)%20(1).pdf Ch 2 (31) (1).pdf 7 / 14 - 90% + | 15.C. General motion has curvy x-t graph that gives rise to curvy v-t and a-t graphs that require Calculus to analyze instantaneous values. To avoid Calculus in this class our x-t graphs will be of only TWO types. Type 1. x-t graph is straight and tilted. Describe what the v-t and a-t graphs look like Type 1. x-t grah is a tilted straight line. HELP: See lecture notes at bottom of page 11. a. Complete the sentence. If the x-t graph is a tilted straight line, then the constant velocity has a value that is the (a word that starts with the letter "'s") of the x-t line and the acceleration has the value (a number) b. Complete the sentence: If the x-t graph is a tilted straight line then the average and instantaneous velocity values are al (a word that starts with the letter "e"). Type 2. x-t graph is a parabola. See lecture notes page 12. c. Complete the sentence. If the x-t graph is a parabola, then the v-t graph has the shape of a tilted (two words), and the constant acceleration has a value that is the_ (a word that starts with the letter "'s") of the v-t line. d. Complete the sentence: if the x-t graph s a parabola then the average and instantaneous acceleration values are always at starts with the letter "e"). 16.C. Our physics Zag class concentrates on "simple motion", that is, motion in which the acceleration is constant (whether 0 or non zero). This is seen in problem 15.C above. Under constant acceleration, the three graphs of x-t, v-t, a-t will have PREDICTABLE fixed shapes with predictable slopes of all straight lines involved. Even though not emphasized for this class (but in more difficult classes), we exploare how to find the instantaneous velocity from average velocity when the x-t graph is curvy but NOT NECESSARILY A PARABOLA. (see below). x [m] 1. Instantaneous velocity at , a Average velocity from f, to iz provided by is close to l 2. U() provided Aris small (1.*2) velocity utta 1 1 , f close to each Activate Windows the fa far from each Go to Settings to activate Windows ^ 024X 1217 AM 3/9/2024 Type here to search SAMSUNGx | * Topic: I made a couple changes X 2ag HCHW Ch 2 (31) (1).pdf * V 2ag HW Ch 1 (20) - Physics Zag x | + X ers/Desktop%20user/Downloads/2ag%20HCHW%20Ch%202%20(31)%20(1).pdf pdf 8 / 14 | - 90% +8) Suppose now that an object moves with x-t equation x = 3 cost graphed below. Assume t is in seconds and x is in meters. a. We want the instantaneous velocity at t, = 2s using the average velocity formula. Explain (using short sentence) why case 2 below would give the better approximation. Case 1. Use t2 = 3s Case 2. Use t2 = 2.1s HELP: See problem 16.C. Read the boxed info. . Based on your answer in part (a), approximate the instantaneous velocity at 2s. HELP: Make sure your calculator is in RADIAN mode for your computation. ANS: 2.66 m/s 17.14. A child operates a remote-controlled toy car on a linear track. The figure below plots the car's position as a function of time (x-t graph). a. Explain how you know this motion has a constant acceleration of 0 for each straight line segment of motion seen in the graph. HELP. See the bottom of page 11 of lecture notes. x (m) Find the velocity (in m/s) of the toy car over the following time intervals. Indicate the direction with the sign of your answer. b. from 0 s to 2 s c. from 2 s to 4 s from 4 s to 6 s e. from 6 s to 9 s f. from 2 s to 6s t ( s ) 18.C. A person who is learning to drive travels backwards and forwards in a straight line in an empty parking lot. Below is a graph of his motion. [mile / hour] Activate Windows Go to Settings to activate Windows. 12:17 AM 3/9/2024 here to search SAMSUNGogram Topic: | made a couple changes x 2ag HCHW Ch 2 (31) (1).pdf x VA Zag HW Ch 1 (20) - Physics 2ag x |+ X C:/Users/Desktop%20user/Downloads/2ag%20HCHW%20Ch%202%20(31)%20(1).pdf a * 2 (31) (1).pdf 9 / 14 | - 90% +| 3 : a. How would you classify the graph above. Circle one the choices: (i) x-t, (ii) v-t, (ii) a-t. b. Looking at the graph, is the velocity changing every instant: yes, or no? HELP: does this velocity graph have a different height at each instant in time. c. True or False: the average velocity 3 mph is a good measure of the center of the car's fluctuating velocity (see dotted line in the graph). d. Was there a time(s) in which the car stopped (i.e. the car was momentary at rest). If yes, then state the time(s). HELP: an object is momentarily at rest at instant t if its velocity is 0 at t. e. If we think of the positive parts of the graph (graph above t axis) as the car moving east, was there any time at which the car moved west: yes, or no? If yes, then state the time interval(s). For example, the form of your answer should look like "from 7 min to 10min". 19.9. a. Name three conditions that will cause a moving object to have a non-zero acceleration. HELP: See lecture notes at the top of page 8 in the box. b. A Ferrari car can go v, =0 to vf = 30- in At = 2.6s Calculate it's acceleration and state by how much the car increases is velocity for each second that goes by. 20.9. A large rubber ball has a speed of 4.0 m/s and moves to the right but once its hits the wall it travels at 2.0 m/s to the left. If it was in contact with the wall for 0.40s, then find the balls average acceleration. Draw pictures to help visualize the velocity vectors 21.16 v [m/s] t [s ] -12) (0, -12) What is the instantaneous velocity at 5s? From the sign, state if the object is moving toward increasing x (right) or decreasing x (left). b. What is the average acceleration from 4s to 9s c. What is the instantaneous acceleration at 7s? HELP: Since the v-t graph from 4s to 9s is a straight line means the acceleration is constant. This means the instantaneous acceleration at any particular time from 4s to 9s is equal to the average value from 4s to 9s. Activate Windows Go to Settings to activate Windows. Jx 12:17 AM 3/9/2024 Type here to search SAMSUNGTopic: I made a couple changes x 2ag HCHW Ch 2 (31) (1).pdf * WA Zag HW Ch 1 (20) - Physics Zag x |+ X ers/Desktop%20user/Downloads/2ag%20HCHW%20Ch%202%20(31)%20(1).pdf 10 / 14 - 90% +| d. Is the object speeding up or slowing down at 5s? Explain how you know. HELP: See boxed rule in lecture notes p.14. e. Is the object speeding up or slowing down at 7s? f. Between what two times is the object moving toward decreasing x (i.e. left). . Yes/No: Is the velocity constant between 9s and 13s? What is its value? What does that mean for the value of the average and instantaneous acceleration values? 22.C. Suppose that a car moves one-dimensionally along the x-axis and has x-t equation x = 15 - 2t, and v-t equation v = -4t , and a-t equation a = -4. Assume all variables are in the standard metric units [m], [m/s] and [m/s2]. a. Compute the car's position, velocity and acceleration at 2s b. If the positive direction of the axis is to the right, then state if the car is moving toward increasing numbers on the axis (right) or decreasing numbers (left) at 2s. c. Draw the car below and draw three vectors: position, velocity, and acceleration at 2s meter HELP: recall that the position vector x is drawn with its tail at the origin but u, a are drawn on the object pointing in the correct direction. d. Is the car speeding up or slowing down at 2s? Explain how you know. e. True or False: If velocity and acceleration are parallel vectors, the object is speeding up, and if they are anti-parallel then it is slowing down 23.C. For the special motion of constant acceleration, we have 4 kinematic equations that fully describe the motion seen below. (1) x= x, + vol + - at' , Ax = vol+- at|(3) v.= vo?+ 2a(x-x). v2=vo+2aAx (2) v= v. + at , Av = at Give a sentence description of each of the variables: x, Xo, Ax = x - Xo, V, Vo, a, t 24.19. A plane is at rest and located 710 m east of the control tower. A student uses the following reference frame (i.e. axis) with the tower at the origin and the positive x axis pointing to the right. Suppose the plane starts at rest and speeds up in the westerly direction with constant acceleration a = -1.5 m/ 2 . The plane has a final take off velocity of v = -130 m/s. 710m a. The 4 kinetic equations below have the following 6 variables: Xo, Vo. x, v, a, t (1) x= x, +w/+zar . Armvoltzar|131 v.=v.?+2a(x-x). v2= vo+2aAx ( 2 ) v= v. + at , Av = at Activate Windows 10 Go to Settings to activate Windows. 12:17 AM pe here to search samsunggram x | R Topic: I made a couple changes * 2ag HCHW Ch 2 (31) (1).pdf X WA 2ag HW Ch 1 (20) - Physics Zag x |+ X C:/Users/Desktop%20user/Downloads/2ag%20HCHW%20Ch%202%20(31)%20(1).pdf C (31) (1).pdf 11 / 14 - 90% + | Identify which of these 6 variables are known (i.e. given) at the start of this problem. b. Explain (using a short sentence) why both a, v are negative for this problem. c. Find the final position x of the plane when it takes off? As part of your work, explain why among the 4 kinematic equations you chose the one you did. d. What is the displacement Ax of the plane from start to take-off? Does it make sense that Ax is negative; explain. HELP: Which way is the vector pointing? . What is the distance that plane moves d before taking off? F. Draw the following vectors on the picture below: initial and final positions, displacement, final velocity, and acceleration. 710m 25.C. a. What is "free fall motion". Describe it in a short sentence. b. Suppose that the positive axis is upward and negative axis is downward. Seen is a snapshot of a rock executing free fall motion. What is sign of its velocity and acceleration? Is the rock slowing down or speeding up? Explain how you know. c. When the rock reaches its maximum height what is the value of its velocity at that moment? d. When it reaches maximum height, its acceleration is still -9.8m/s': yes, or no? e. True or False: to solve free fall motion problems, use the 4 kinematic equations for constant acceleration and simply replace a with -9, that is to say a = -9.82. f. Look at the notes: we see that the letter "g" is the magnitude of the acceleration vector. As a magnitude which is correct: g = 9.8 m/s or g = -9.8 m/s2 ? What is true about the sign of the magnitude of any vector? Using the standard direction of north/south axes where positive is up, when an object is in free fall is the vector component a = g = 9.8 2 or a = -g = -9.8! ? 26.C. a). The "magnitude" of a vector is its size. Every magnitude is always positive: yes, or no? b). Given the coordinate system seen to the right, increasing numbers are upward and decreasing numbers are downward. Any vector with a negative value must point up or down? If a vector is a positive number, then which way does it point (north or 6 - 5 - 4 -5 -2 -1 0 1 2 3 4 5 6 south)? Activate Windows Go to Settings to activate Windows. x 12:17 AM * 3/9/2024 Type here to search SAMSUNGx | * Topic: | made a couple changes x 2ag HCHW Ch 2 (31) (1).pdf x x 2ag HW Ch 1 (20) - Physics Zag x | + X C:/Users/Desktop%20user/Downloads/2ag%20HCHW%20Ch%202%20(31)%20(1).pdf a * C : (31) (1).pdf 12 / 14 - 90% + ). A student is doing a free fall problem on a baseball thrown vertically upward. He finds that at a particular instant that x = +5m, v = +3m/s and a =-9.8m/s2. If you think of the origin as the earth's surface, then draw and lable the three vectors: position x , velocity , and acceleration a on the axis seen to the right. -2 -1 0 1 2 3 4 5 6 + HELP: Recall that position vectors have their tail at the origin and tip at the object and velocity and acceleration are drawn on the object. 1). For the numbers given in part (c), is the object slowing down or speeding up? Explain how you know with a short sentence. e). A student makes the statement "if at an instant, the acclerating and velocity of an object have opposite signs then the object is slowing down". Is he correct? Yes, or no? f). A student makes the statement "if at an instant, the accleratingand velocity vectors point in the same direction, then the object is slowing down". He is incorrect. Correct his statement. 27.21. A ball is thrown into the air with an initial speed vo =19 m/s from the height of a person's head, h = 1.6m. Choose the positive direction of the axis as upward like in the previous problem and the origin to be ground level. a. How high above the ground does the ball travel before turning around? b. How long is the ball in the air? c. What is the acceleration and velocity at 1.6s? d. What is the acceleration and velocity at 2.3s? e. What is the ball's velocity and speed when it hits the 19 m/ s ground? HELP: speed is a scalar and represents the magnitude of the velocity vector, so it is always positive. Speed can be found, like all magnitudes for one-dim vectors, by taking the absolute value of the vector. 1.6m 28.22. a. Our class meets from 7pm to 10pm. What is the duration At (i.e., elapsed time) b. Suppose that someone in the class had a stopwatch and as soon as class started, he used the stopwatch to keep track of class time. What number does any stopwatch start at when you hit start? What number would the stopwatch read at the end of class? c. You can see that parts (a) and (b) give the same answer of 3 hours True or false: when using any physics equation that involves time, if the student always sets the initial time to 0, then At gives the same number as t. d. In chapter 16 we will study the Heat Conduction Equation ~=-A . In this equation T is temperature and t is time. Given your answer to part (c), how might you Activate Windows rewrite this equation for the time part? 12 Go to Settings to activate Windows. ~ 924 1217AM Type here to search 3/9/2024 SAMSUNG| Topic: I made a couple changes x 2ag HCHW Ch 2 (31) (1).pdf