SOLUTIONS PHY111 Fall 2013 Exam 3 y Part A. The scale of the vectors shown is of one MKS unit (of force, velocity, or distance) per square. The objects P, Q, R are also shown. F1 1. An object is in a circular path around the origin. At a given V2 Q time, it is observed to have velocity V, and to pass by the V1 position of this vector. If the object maintains a constant X velocity magnitude, what is the period of the motion? (In seconds). Solution: The speed is 3 m/s. The radius of the circle is 3 m. P R For a full cycle we have v=2ntR/T. So T= 2ntR/V=2n(3)/3=21. (A) 1/(21) O(B) 2n (C) 1 (D) 1/(61) (E) 61 2. An object is in a circular path around the origin. At a given time, it is observed to have velocity V, and to pass by the position of this vector. If the object maintains a constant velocity magnitude, what is the magnitude of its acceleration? (In m/s ). Solution: The magnitude of the acceleration is a=v3/R=(3)3/3=3 m/s?. (A) O (B) 1/3 O (C) 3 (D) 9 (E) 27