Total 0/30. 0/1 points Walker3 2.P.068. [544577]

Transcription

1 9/9/13 Aignent Previewer Phy 111.HW#2b ( ) Current Score: 0/30 Due: Wed Sep :30 AM PDT Quetion Point /1 0/2 0/3 0/3 0/3 0/3 0/1 0/1 0/1 0/6 0/6 Total 0/30 Decription You can avoid any itake, if you tick on thee rule for chapter 2. 1, alway define your poitive direction and origin firt. Stick on your poitive direction defination!. 2, never eorize equation like v=qrt(2ax), we need to learn how to olve proble uing genral equaition that are alway true. pecial cae equation only work for pecial condition when v0=0, etc. Don't eorize the! 3, alway carefully identify known and unknown variable. Pay attention to poitive and negative ign. 4, Never aue unknown thing to be zero. 5, Initial v and poition do not change, but v, x and delta x keep changing. Which part of otion are you tudying? Which point i the final point? One proble can ak you a few different quetion with different "final" location. (at axiu height, where vf=0); (back to grounf, where vf i unknown, but deltax i known...) Study HW olution online and be prepared for quizze. Intruction For quetion 2: In thi quetion they don't ak you the poition at t=5 or t=0.3. It want you to how poition x a a function of t. The webaign i not a art a a real huan intructor... :) It doen't reorganize your anwer unle you follow it ybolic rule, which are not hard if you pay attention. Actually we practiced how to anwer thi kind of quetion in Intro to webaign for phy. Pleae review quetion 10 in the firt aignent Intro to webaign for phy. In that quetion, it how you a right triangle. The two ide length are a and b repectively. They ak you the length for the hypotenue, c. You know that The quare on the hypotenue i equal to the u of the quare on the other two ide.. So, c=(a^2 +b^2)^1/2 ; Check what you need to input into the box to anwer that quetion: 1, you hould not include the ign = ; 2, you hould not include the whole equation,; You hould only put the right ide of your anwer in the box, : (a^2 +b^2)^1/2; 3, you need the right forat: you can type: qrt(a^2+b^2) ; you can alo type: qrt(a*a+b*b) ; you can alo type: (a^2+b^2)^0.5; Sae thing for thi quetion, do not put = in your anwer. Jut put the right ide of your function of potion x = blah blah g and blah blah t... into your box: For exaple, If you believe that Bill' poition x at tie t will be equal to t g + (1/2 * g^2 ) 5t You jut put t g +( 1/2 * g^2 ) 5t in the box. DO NOT PUT x=123 + t g + (1/2 * g^2) 5t in the box. Notice that you hould ue g intead of 9.8 for anwering thi one. You can clearly ee the exaple anwer above i not correct, jut to how you the way of foratting Alo poitive or negative ign are very iportant. When the anwer i arked wrong, oething i wrong. Think ore clearly and try ore. Learn fro itake. Dr. Man: Right. it i iportant to realize that one equation with gravity acceleration will decide the whole otion after juping up. You do not need to break it into two part of otion.v= v0+ at and x=x0+v0 t+1/2 a t^2 are valid for any tie after juping. (before and after the axiu point) v0 and x0 are fixed. a i alo fixed. Pay attention to their ign. 1. 0/1 point Walker3 2.P.068. [544577] Seagull are often oberved dropping cla and other hellfih fro a height to the rock below, a a ean of opening the hell. If a eagull drop a hell fro ret at a height of 15, how fat i the hell oving when it hit the rock? / 1/5

2 9/9/13 Aignent Previewer 2. 0/2 point Walker3 2.P.072. [544508] Bill tep off a 2.8 high diving board and drop to the water below. At the ae tie, Ted jup upward with a peed of 4.0 / fro a 1.0 high diving board. Chooing the origin to be at the water' urface, and upward to be the poitive x direction, write the xverut of otion for both Bill and Ted. (Ue g and t, a neceary.) Bill Ted 3. 0/3 point Hot air balloon (p111) [416140] A hot air balloon i riing upward with a contant peed of 5 /. When the balloon i 4 above the ground, the balloonit accidentally drop a copa over the ide. a.) How uch tie elape before it hit the ground? b.) What i it peed jut before it hit the ground? / c.) How high above the ground i the balloon when the copa hit the ground? 4. 0/3 point Diver. (p111) [416146] A diver pring upward with an initial peed of 6 / fro a diving board that i 5 above the water. a.) What i the axiu height the diver reache above the water? b.) Find the total tie the diver i airborne. c.) Will the diver pend ore tie travelling upward or downward? Explain. 2/5

3 9/9/13 Aignent Previewer 5. 0/3 point Walker3 2.P.032. [544619] A otorcycle ove according to the velocityverutie graph hown in Figure 231. (The vertical axi i arked in increent of 2 / and the horizontal axi i arked in increent of 7.) Find the average acceleration of the otorcycle during each of the egent of otion, A, B, and C. a A = / 2 a B = / 2 a C = / 2 Figure /3 point Walker3 2.P.033. [544711] A peron on horeback ove according to the velocityverutie graph hown in Figure 232. (The vertical axi i arked in increent of 1 / and the horizontal axi i arked in increent of 6.) Find the diplaceent of the peron for each of the egent A, B, and C. A = B = C = Figure /1 point Walker3 2.P.050. [544610] A 27 pound eteorite truck a car, leaving a dent 19 c deep in the trunk. If the eteorite truck the car with a peed of 510 /, what wa the agnitude of it deceleration, auing it to be contant? / 2 3/5

4 9/9/13 Aignent Previewer 8. 0/1 point Walker3 2.P.071. [544584] Here' oething you can try at hoe an experient to eaure your reaction tie. Have a friend hold a ruler by one end, letting the other end hang down vertically. At the lower end, hold your thub and index finger on either ide of the ruler, ready to grip it. Have your friend releae the ruler without warning. Catch it a quickly a you can. If you catch the ruler 5.6 c (~2.2 inche) fro the lower end, what i your reaction tie? 9. 0/1 point Walker3 2.P.070. [544511] The firt active volcano oberved outide the Earth wa dicovered in 1979 on Io, one of the oon of Jupiter. Suppoe a volcano on another oon i oberved to be ejecting aterial to a height of about Given that the acceleration of gravity on thi oon i 1.69 / 2 find the initial velocity of the ejected aterial. / 10. 0/6 point Practice with vector [417916] Practice with vector: (iportant!) For each of the vector below, I.) do a rough ketch of it II.) convert it to the for it i not already in (ize&direction, or coponent) (Note: cw=clockwie, ccw=counterclockwie) a.) = 5, 50 o ccw fro +x axi D x = D y = b.) av = 15 /, 10 o cw fro y axi v av x = v av y = / / c.) Q x = 3, Q y = +4 =, o cw fro x axi 4/5

5 9/9/13 Aignent Previewer 11. 0/6 point Walker3 3.P.029 [ ] Ue unit vector notation to expre each of the vector in Figure 339, in which the agnitude of A, B, C, and D are repectively given by 6, 8, 4, and 6. A = ( x + y) B = ( x + y) C = ( x + y) Figure 339 Aignent Detail Nae (AID): Phy 111.HW#2b ( ) Subiion Allowed: 7 Category: Hoework Code: Locked: Ye Author: Man, Weining ( weining@fu.edu ) Lat Saved: Feb 20, :37 PM PST Periion: Protected Randoization: Peron Which graded: Lat Feedback Setting Before due date Quetion Score Aignent Score Publih Eay Score Quetion Part Score Mark Add Practice Button Help/Hint Repone Save Work After due date Quetion Score Aignent Score Publih Eay Score Key Quetion Part Score Solution Mark Add Practice Button Help/Hint Repone 5/5