MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

Transcription

1 PHYS 101 Fall 2013 (Purcell), Fake Midterm #1 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The figure shows the graph of the position x as a function of time for an object moving in the straight line (the x-axis). Which of the following graphs best describes the velocity along the x-axis as a function of time for this object? 1) A) B) C) D) E)

2 2) A car accelerates from 10.0 m/s to 30.0 m/s at a rate of 3.00 m/s 2. How far does the car travel while accelerating? A) 80.0 m B) 226 m C) 399 m D) 133 m 2) 3) The figure represents the velocity of a particle as it travels along the x-axis. At what value (or values) of t is the instantaneous acceleration equal to zero? 3) A) t = 0.5 s and t = 2 s B) t = 1 s C) t = 0 4) Which of the following is an accurate statement? A) The magnitude of a vector is independent of the coordinate system used. B) It is possible to add a scalar quantity to a vector. C) Rotating a vector about an axis passing through the tip of the vector does not change the vector. D) The magnitude of a vector can be zero even though one of its components is not zero. E) Even though two vectors have unequal magnitudes, it is possible that their vector sum is zero. 4) 5) Two objects are thrown from the top of a tall building and experience no appreciable air resistance. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street? A) The one thrown up is traveling faster. B) They are traveling at the same speed. C) The one thrown down is traveling faster. 5) 6) Vector A = -1.00i^ j^ and vector B = 3.00 i^ j^. What are the magnitude and 6) direction of vector C = 3.00A B? A) 5.00 in a direction 56.3 counterclockwise from the positive x axis B) 6.72 in a direction 34.4 counterclockwise from the positive x-axis C) 3.61 in a direction counterclockwise from the positive x-axis D) 3.61 in a direction 56.3 counterclockwise from the positive x-axis E) 3.61 in a direction 33.7 counterclockwise from the positive x-axis

3 7) Shown below are the velocity and acceleration vectors for a person in several different types of motion. In which case is the person slowing down and turning to his right? A) 7) B) C) D) E) 8) If an object is accelerating toward a point, then it must be getting closer and closer to that point. A) True B) False 8) 9) Under what condition is A - B = A + B? 9) A) Vectors A and B are in perpendicular directions. B) Vectors A and B are in opposite directions. C) Vectors A and B are in the same direction. D) The magnitude of vector B is zero. E) The statement is never true. 10) A plot of land contains 5.8 acres. How many square meters does it contain? [1 acre = 43,560 ft 2 ] A) m 2 B) m 2 C) m 2 D) m 2 10)

4 11) You want to swim straight across a river that is 76 m wide. You find that you can do this if you swim at an angle of! = 28 from the upstream direction at a constant rate of 1.5 m/s relative to the water. At what rate does the river flow? The angle! is measured from the river bank (directly upstream is! = 0 while directly across the river is! = 90 ). A) 1.8 m/s B) 1.3 m/s C) 1.6 m/s D) 0.70 m/s 11) 12) Jan and Len throw identical rocks off a tall building at the same time. The ground near the building is flat. Jan throws her rock straight downward. Len throws his rock downward and outward such that the angle between the initial velocity of the rock and the horizon is 30. Len throws the rock with a speed twice that of Jan's rock. If air resistance is negligible, which rock hits the ground first? A) Len's rock hits first. B) They hit at the same time. C) Jan's rock hits first. D) It is impossible to know from the information given. 12) 13) A ball is thrown at a 60.0 angle above the horizontal across level ground. It is thrown from a height of 2.00 m above the ground with a speed of 20.0 m/s and experiences no appreciable air resistance. The time the ball remains in the air before striking the ground is closest to A) 16.2 s. B) 3.64 s. C) 3.53 s. D) 3.32 s. E) 3.07 s. 13) SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 14) A rock is thrown directly upward from the edge of the roof of a building that is 66.2 meters tall. The rock misses the building on its way down, and is observed to strike the ground 4.00 seconds after being thrown. Neglect any effects of air resistance. With what speed was the rock thrown? 14) 15) Vector A has a magnitude of 75.0 cm and points at 30 above the positive x-axis. 15) Vector B has a magnitude of 25.0 cm and points along the negative x-axis. Vector C has a magnitude of 40.0 cm and points at 45 below the negative x-axis. (a) Determine the x and y components of Vector A. (b) Determine the x and y components of Vector B. (c) Determine the x and y components of Vector C. (d) Determine x and y components of the sum of these three vectors. (e) Determine the magnitude and direction of the sum of these three vectors.

5 Answer Key Testname: PHYS101_FALL2013_FAKEMIDTERM1 1) D 2) D 3) B 4) A 5) B 6) E 7) E 8) B 9) B 10) A 11) B 12) B 13) B 14) 3.05 m/s 15) (a) A x = 65 cm, A y = 38 cm (b) B x = -25 cm, B y = 0 (c) C x = -28 cm, C y = -28 cm (d) R x = 12 cm, R y = 9.2 cm (e) 15 cm at 38 above +x-axis