Physics 1111 Exam #1 2:30-C Solutions8 February 2019 Name:Physics 1111Exam #1 2:30-C SolutionsInstructions:This is a closed-book, closed-notes exam. You will be given a separate sheet of formulas andnumerical data that you may consult. Nothing written on the formula sheet will begraded.There is space after each question to show your work; if you need more space, you may usethe back of the page, or request more paper. Please clearly indicate where your work foreach problem is. Underline or draw a box around your final answer.The exam consists of five sections. I recommend that you read all the questions at the startso that you can allocate your time wisely.You may use a scientific calculator for arithmetic only; your calculator must be non-graphing,non-programmable, and non-algebraic. You are not allowed to share your calculator.The use of cell phones, PDAs, or any other electronic devices (besides calculators) is forbid-den. All such gadgets must be turned off and put away throughout the exam.• Do not open the exam until told to begin.• You have one class period (50 minutes) to finish the exam.• Make sure every page of the exam has your last name.• You must provide explanations and/or show work legibly to receive full credit forParts III–V.• Make sure that your answers include appropriate units and significant digits.• Assume that air resistance is negligible, unless otherwise stated.By signing below, you indicate that you understand the instructions for this exam and agreeto abide by them. You also certify that you will personally uphold the university’s standardsof academic honesty for this exam, and will not tolerate any violations of these standards byothers. Unsigned exams will not be graded.Signature:UGA ID (81x) #: Row/Seat:Copyrightc 2019 University of Georgia. Unauthorized duplication or distribution prohibited.Physics 1111 Exam #1 2:30-C Solutions8 February 2019 Last Name:Part I II III IV B Total Score GradeScore /12 /27 /40 /21 /100 /100I: Multiple-Choice Questions (12 points)For each question below, choose the single best response and write the correspondingcapital letter in the box provided. There is no penalty for guessing.1. Marie wants to kayak across a river. The current flows from north to south at speedv, and Marie can paddle at a speed 2v in still water. In what general direction shouldshe head to cross the river to the east bank in the least amount of time?BA. North of East.B. Due East.C. South of East.D. The three directions take the same amount of time.2. A kicker kicks a football from ground level at the 10-yard line to the 50-yard line.Where along the trajectory is the football’s speed a minimum?CA. At the 50-yard line, just before the football lands.B. At the 40-yard line.C. At the 30-yard line.D. At the 20-yard line.E. At the 10-yard line, just after the football leaves the kicker’s foot.F. The speed is the same throughout.3. A car’s brakes produce a constant-magnitude acceleration. For some initial speed, thestopping distance of the car is d. If the initial speed doubles, what will be the newstopping distance?DA. d/2B. dC. 2dD. 4dE. 8dCopyrightc 2019 University of Georgia. 2Physics 1111 Exam #1 2:30-C Solutions8 February 2019 Last Name:II: Order/Choice Questions (27 points)For each question below, write your responses in capital letters in the space provided.1. Each of the graphs below shows position, velocity, or acceleration plotted versus time,for an object in motion along a straight line.A B CtxtvtaD E FtxtvtaIn the space provided, identify in capital letters all graphs meeting the stated con-dition. Write “none” if no graphs satisfy the condition.(a) Velocity is constant. A, F(b) Acceleration is constant. A, B, E, F(c) Total displacement is zero over the time interval shown. B(d) Velocity reverses direction. B(e) Velocity increases over the whole time interval shown. C, E2. Four projectiles are launched with different ini-tial speeds so that they reach the same maximumheight, as shown. Rank the trajectories in order ofincreasing initial speed. Be sure to note if any ofthe initial speeds are equal. Use less-than symbolsand equals signs (<, =) to indicate rankings.B <C <D <AxABCDCopyrightc 2019 University of Georgia. 3Physics 1111 Exam #1 2:30-C Solutions8 February 2019 Last Name:III: Table Slide (40 points)Abby shoves her physics textbook horizontally from the left end of a long table with aninitial speed of v0= 6.20 m/s. The book then slides the length of the table and shoots offthe right end with speed v1= 5.10 m/s, landing on the floor a distance d to the right of thetable. The table is ` = 2.80 m long and h = 0.950 m high.v0v1(a) What was the acceleration (magnitude and direction) of the book as it slid the lengthof the table?(8 points) The first two parts of this problem are 1-D motion. There are two events toconsider for this part of the motion, the moment the book is given its initial velocity, andthe moment it leaves the table. Let’s call them Event 0 and Event 1, respectively. As usual,a table can be useful here. Let’s take the origin to be the starting point, and the directionof motion (right) as positive.Event 0 Event 1t t0= 0 s t1=?x x0= 0 m x1= 2.80 mvxv0x= 6.20 m/s v1x= 5.10 m/saxax=?The most direct way to find the accelera-tion would be to use the kinematic equationv2fx= v2ix+ 2ax(∆x). Using the appropriatequantities here gives:v21= v20+2a` =⇒ a =v21− v202`=(5.10 m/s)2− (6.20 m/s)22(2.80 m)= −2.21964 m/s2' −2.22 m/s2.The negative sign means that the acceleration is to the left.If you chose to find time first, then v1= v0+ at1would be a convenient way to findacceleration.(b) How long did it take for the book to reach the far end of the table?(7 points) We have lots of options for this part, particularly if we have found accelerationin Part (a). However, we can find time without acceleration:` =12(v0+ v1)t1=⇒ t1=2`v0+ v1=2(2.80 m/s)6.20 m/s + 5.10 m/s= 0.495575 s ' 0.496 s.If we already have a, another option would be to use v1= v0+ at1. Yet another optionwould be to use ∆x = vit +12at2. This requires solving a quadratic, which will give us twopositive answers. In this case, we would want the shorter time, since that would be whenthe book first reaches the end of the table.Copyrightc 2019 University of Georgia. 4Physics 1111 Exam #1 2:30-C Solutions8 February 2019 Last Name:III: cont.(c) How long was the book in the air?(8 points) In the next three parts, we are dealing with