UIC Physics 105

Midterm Practice Exam 1

Spring 2013

Best if used by February 17

PROBLEM Multiple Choice Short Problem 1 Short Problem 2 Short Problem 3 Short Problem 4 Short Problem 5 Short Problem 6 Total POINTS 40 10 10 10 10 10 10 100 SCORE

Page 1 of 11

UIC PHYSICS 105 Spring 2013 Practice Exam 1

MULTIPLE CHOICE QUESTIONS (2 points each) Clearly circle the letter of the best answer MCQ 1: The figure to the right represents the position of a particle as it travels along the x-axis. At what value of t is the velocity of the particle equal to zero? (A) 1 s Answer: velocity = slope of x vs t line (B) 2 s slope = 0 at t = 3 s (C) 3 s (D) 4 s

MCQ 2: A runner runs around a track consisting of two parallel lines 96 m long connected at the ends by two semicircles with a radius of 49 m. She completes one lap in 100 seconds. What is her average velocity? (A) 2.5 m/s ∆ (B) 5.0 m/s Answer: 0 m/s ∆ ∆ (C) 10 m/s (D) 0 m/s MCQ 3: You drop a very bouncy rubber ball. It falls, and then it hits the floor and bounces right back up to you. Which of the following represents the v vs. t graph for this motion?

Answer: Initially, the ball is falling down, so its velocity must be negative (if UP is positive). Its velocity is also increasing in magnitude as it falls. Once it bounces, it changes direction and then has a positive velocity, which is also decreasing as the ball moves upward. MCQ 4: Two objects are dropped from a bridge, an interval of 1.0 s apart. During the time that both objects continue to fall, their separation Object 1: , . (A) increases. (B) decreases. Object 1: , . (C) stays constant. If t1 > t2 , , , , , , (D) increases at first, but then stays constant. then and the separation between two objects x1 – x2 increases

Page 2 of 11

UIC PHYSICS 105 Spring 2013 Practice Exam 1

MCQ 5: Given that and that each other? (A) they are perpendicular to each other (B) they are parallel and in the same direction (C) they are parallel but in the opposite direction (D) they are at 45° to each other

, how are vectors and oriented with respect to Answer: The only time vector magnitudes will simply add together is when the direction does not have to be taken into account (i.e., the direction is the same for both vectors). In that case, there is no angle between them to worry about, so vectors A and B must be pointing in the same direction.

MCQ 6: You are adding vectors of length 20 and 40 units. What is the only possible resultant magnitude that you can obtain out of the following choices? Answer: (A) 18 The minimum resultant occurs when the vectors are (B) 37 opposite, giving 20 units. The maximum resultant occurs (C) 64 when the vectors are aligned, giving 60 units. Anything in (D) 100 between is also possible for angles between 0° and 180°. MCQ 7: A train is moving in the west direction with a velocity 15 m/s. A monkey runs on the roof of the train against its motion with a velocity 5 m/s with respect to train. Take the motion along west as positive. The velocity of train with respect to monkey is Answer: (A) 5m/s velocity of train=15m/s (B) 5 m/s velocity of monkey relative to the train=5 m/s (C) 15 m/s Now velocity of monkey relative to the train = velocity of (D) 15 m/s train with respect to monkey So velocity of train with respect to monkey=5 m/s MCQ 8: Two particles start from the origin of the horizontal x-y plane. Particle A moves along +x axis with speed v. Particle B moves along y axis with the same speed v. The relative velocity of particle B with respect to A is Answer: (A) m/s Velocity of A is m/s (B) m/s m/s Velocity of B is (C) 0 m/s velocity of B with respect to A m/s (D) m/s MCQ 9: A rock of mass m is thrown horizontally off a building from a height h, as shown in the figure to the right. The speed of the rock as it leaves the thrower’s hand at the edge of the building is v0. How much time does it take the rock...