Physics 121 Exam 1 Fall 2022 PDF

∗ ∗ ∗ ∗ Motion !&,G = −!&,7 , !',G = −!',7 Math opp !" !$ #"...

∗ ∗ ∗ ∗ Motion !&,G = −!&,7 , !',G = −!',7 Math opp !" !$ #" sin G = , != !# , #= !# , ∫#!.⃗9.# = 5> 6, ' I :14$ = −2 1 , !# !A(") L@⃗7 = L @⃗G ,.(&) = − !" , Simple harmonic motion Momentum &(%) = Rcos(E% + V), B; 1⃗ -@⃗/; = B;# # , # > 'Q E = W;, X = J A@⃗#(#42 = B#(#42 C @⃗/; , !DE⃗$%$&' =.⃗9.#,."# , !# A@⃗7 = A@⃗G , Physics 121 9/16/22 Exam 1 LAST namecccccccccccccccFirst name______________________ Physics 121 exam instructions Section Day and time 9 AM Lecture sections: PLEASE TEAR OFF THE COVER SHEET AND TAKE IT WITH YOU 02 W 5:00-6:50 PM CIRCLE YOUR DISCUSSION SECTION AT RIGHT 03 Th 8:00-9:50 AM Calculator OK; no sharing permitted 04 Th 11:30-1:20 PM No phones, books, notes, headphones, or earbuds. Standards for academic integrity will be enforced as described in the syllabus. 05 Th 2:30-4:20 PM Be prepared to present your UMBC ID. 06 W 5:00-6:50 PM For free-response items, show clear evidence of your reasoning process, 08 Th 8:00-9:50 AM unless otherwise indicated. A correct response without supporting work will 09/14* Th 5:00-6:50 PM receive no credit. An incorrect response may receive partial credit on the basis of clear, complete, and correct supporting work. 11 AM Lecture sections* For numerical items, give your result to two significant figures with 11* W 1:00-2:50 PM appropriate units. 12* Th 11:30-1:20 PM (1 pt for legible name and correct section circled) 13* Th 2:30-4:20 PM 15* W 7:00-8:50 PM (1-2) Consider the vector at right. 1. What are the x- and y-components of the vector? Include the correct signs. (2 pts, no work required) x-component: ________ y-component: ________ 2. What is the magnitude of the vector? (1 pt, no work required) 3. What angle does the vector at right make with the +x-axis, in degrees? (1 pt, no work required) (4-5) An object moves according to the v-t graph at right. 4. How far does it go in the time interval 1.0 s < t < 2.0 s? (2 pts) 3 a. 5.0 m 2 v(m/s) b. 4.0 m 1 c. 2.5 m d. 2.0 m 0 -1 0 1 2 3 5. Does the object ever change direction? (1 pt) -2 a. Yes, at t = 2 s -3 b. Yes, at t = 2.75 s c. No t(s) (6-7) An object moves according to the x-t graph at right. 6. Matching: (One is done for you. There will be two unused choices.) (3 pts) Instantaneous velocity at t = 2.0 s 0 Average velocity for 2.0 s < t < 5.0 s 1.0 m/s Instantaneous velocity at t = 5.0 s 2.4 m/s Average velocity for 0 s < t < 5.0 s 3.0 m/s 4.0 m/s 6.0 m/s 7. (1 pt) For what time interval is the acceleration negative? a. 0 s < t < 2.0 s b. 2.0 s < t < 5.0 s c. Actually the acceleration is never negative (8-10) You can swim with a speed of 1.5 m/s in still water. You manage to swim to the point directly across a stream from your starting point, as shown, despite the stream’s 1.0 m/s current, as shown in the figure. swimmer’s water 1.0 m/s path 8. What angle should you aim your body? (How many degrees upstream from straight across?) (2 pts) a. 42° b. 34° c. 30° 9. What’s the magnitude of your velocity (how fast are you going) relative to Earth? (2 pts) a. 0.50 m/s b. 1.1 m/s c. 1.8 m/s 10. If instead you just aimed your body straight across the stream, would it take you more time or less time to cross the stream? (1 pt) a. It would take more time to cross if you aimed your body straight across b. It would take less time to cross if you aimed your body straight across c. Wouldn’t matter, it would take the same time to cross either way 11. The figure shows the path of a projectile. At t = 2.0 s, the projectile is going 30 m/s. How fast is it going (what’s the magnitude of its velocity) at t = 3.0 s? Use g = 10 m/s2. (2 pts) a. 30 m/s b. 32 m/s c. 36 m/s d. 40 m/s 12. After some local competitions, you’ve made it to the cliff diving World Championships. The cliff is 45 m high, and there’s a rocky outcrop at the bottom that goes out 6.0 m. You run straight off the horizontal edge of the cliff. To make certain you clear the rocks, how fast do you need to run? Use g = 10 m/s2. (5 pts) 13. A car at rest at a traffic light starts to move forward the instant a truck moving at a constant 12 m/s passes. The car immediately begins to speed up at a rate of 4.0 m/s2. How much time and distance does it take the car to catch the truck? Show your work and give units. (8 pts)