CT3-1Test your transmitter by answering this question. Find the nearest receiver that is pointing at you. Double check your transmitter ID.The solid line has length A and makes an angle with the negative y-axis. What is the length of the dotted line?A: A cosB: A sinC: A tanD: sin/AE: cos/AAnswer: +A cosCT3-1bWhat is the correct formula for Ay, the y-component of the vector A?A: A cosB: A sinC: -A cosD: -A sinE: None of these.Answer: -A sinx y A xyANote: if we measured the angle CCW from the positive x-direction (as shown below), then the answer would be Ay = +A sinCT3-2a Can two vectors of unequal magnitude sum to zero?A: Yes. B: No.Answer: NO. The only way two vectors can sum to zero is if they have equal and opposite directions, like so: CT3-2b Can three vectors of equal magnitude sum to zero?A: Yes. B: No.Answer: If they form the sides of an equilateral triangle, then, yes, they sum to zero.xyACT3-3 Vectors C and ,B,A sum to zero. Vectors B and A are at right angles to each other. What is the magnitude of C, C?A: A+BB: A–BC: 22BA D: Impossible to tell from the information given.Answer: By the Pythagorean Theorem, the answer is 22BA CT3-4Three vectors A B and C, , are as shown. Which vector is S A B C ?ABCAnswer: None of these. The correct answer is below.(A) (B) (C) (D)ABC(E) None of these.(A) (B) (C) (D)AB-C(E) None of these.A+B-CCT3-5.The position vector of a particle moving with constant velocity is shown below at two different times, an earlier time t1 and a later time t2. Which arrow shows the direction of the velocity vector? Answer: (B) By looking at the position vectors, you can see that the particle is moving to the right. (A) (B) (C) (D)(E) None of these!R1R2CT3-6.The velocity vector of a particle moving with constant acceleration is shown below at twodifferent times, an earlier time t1 and a later time t2. What is the direction of the acceleration vector?Answer: (C) The acceleration vector is straight down, the same direction as the change invelocity vector. vatD=Drr(A) (B) (C) (D)(E) None of these!V1V2V1V2VCT3-7 The vectors A, B, and Cr rr are shown. The vector sum of these three vectors is S = A + B + Cr r rrWhat is the value of Sx, the x-component of Sr?A: +2B: -4C: -2D: +3E: None of theseAnswer: Sx =Ax + Bx +Cx = +3 - 3 - 3 = -3What is Sy? Answer: Sy =Ay + By +Cy = -1 - 3 + 0 = -4A C BCT3-8 Which one equation below makes no sense?A: �A jurB: � � �B 3i j 5j urC: � �C 3i 4j urD: ˆD A i= +ur urE: All equations above are OK.Answer: All these equation are OK. NOTE: In lecture, choice (D) was written as ˆC A i= +ur ur, which caused some students to think that must be incorrect, since it conflicts with the equations given in A) and C). Full credit was given for either answers D or
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