Midterm exam 2017, questions PDF

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Midterm exam 2017, questions...

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Physics 117 Mock Midterm Sunday, February 11, 2018 * 1 pm – Room 241 Arts Building *

Note: This mock test consists of questions covered in Physics 117. This test is not comprehensive. The problems on this test were compiled by your SSS peer mentors, and not your professors, and are based on problems from the textbook College Physics, Raymond Serway and Chris Vuille (9th, 10th, and 11th editions) and old exams from the website http://physics.usask.ca/~bzulkosk/phys117/index.html . **This mock test should not be viewed as a ‘preview’ of the actual test, and you should not rely solely on it for your test preparation.** Phys 117 Structured Study Session Information Mondays 4:30-5:50pm - Room 102 in the Murray Library (Yen) Tuesdays 2:30-3:50pm – Room 104 in the Arts Building (Michael) Wednesdays 3:30-4:50pm – Room G3 in the Murray Library (Yen)

Student Learning Services (SLS) is a unit of the University Library that offers learning support to students. You can find information about the following services for students on the SLS website (http://library.usask.ca/studentlearning): • Study Skills • Writing Help • Math & Stats Help • Structured Study Sessions for Phys 117, Bio 120, and Chem 112 • Workshops on topics such as research skills, exam preparation, etc. Visit the University Library website (http://library.usask.ca) for information on other Library services and programs.

2 Part A – Multiple Choice Questions 1. A hydraulic jack has an input piston of area 0.050 m2 and an output piston of area 0.70 m2 . How much force on the input piston is required to lift a car weighing 1.2 × 103 N. (a) 42 N

(b) 68 N

(c) 86 N

(d) 110 N

(e) 130 N

2. A horizontal pipe narrows from a radius of 0.250 m to 0.100 m. If the speed of the water in the pipe is 1.00 m/s in the larger-radius pipe, what is the speed in the smaller pipe? (a) 4.50 m/s

(b) 2.50 m/s

(c) 2.50 m/s

(d) 6.25 m/s

(e) 5.13 m/s

3. A boat develops a leak and, after its passengers are rescued, eventually sinks to the bottom of a lake. When the boat is at the bottom, the force of the lake bottom on the boat is … (a) (b) (c) (d) (e)

greater than the weight of the boat equal to the weight of the boat less than the weight of the boat equal to the weight of the displaced water equal to the buoyant force on the boat

4. A tensile force ฀฀ stretches a wire of original length ฀฀ by an amount ∆฀฀. Consider another wire of the same composition and thickness as the first wire, but of length 2฀฀. If a force of 2฀฀ is applied to this wire of length 2฀฀, then the amount that it stretches is … (a)

1 4

∆฀฀

1

(b) 2 ∆฀฀

(c) ∆฀฀

(d) 2∆฀฀

(e) 4∆฀฀

5. If the amplitude of a system moving in simple harmonic motion is doubled, which of the following quantities does not change? (a) total energy (b) maximum speed (c) maximum acceleration (d) period 6. An object of mass ฀฀ attached to a horizontal spring, stretched to a displacement ฀฀ from equilibrium, and released, undergoing harmonic oscillations on a frictionless surface with period ฀฀0 . The experiment is then repeated with a mass of 4฀฀. What is the new period of oscillation? (a) 2฀฀0

(b) ฀฀0

(c)

1 2

฀฀0

(d)

1 ฀฀ 4 0

7. A block on the end of a horizontal spring is pulled from equilibrium at ฀฀ = 0 to ฀฀ = ฀฀ and released. Through what total distance does it travel in one full cycle of its motion? ฀฀ (a) (b) ฀฀ (c) 2฀฀ (d) 4฀฀ 2

Answers will be posted on the Structured Study Session web page: http://library.usask.ca/sss

3 8. For a simple harmonic oscillator, which of the following pairs of vector quantities can't both point in the same direction? (The position vector is the displacement from equilibrium.) (a) position and velocity (b) velocity and acceleration (c) position and acceleration (d) force and acceleration 9. Suppose you’re on a hot air balloon ride, carrying a buzzer that emits a sound of frequency ฀฀. If you accidentally drop the buzzer over the side while the balloon is rising at constant speed, what can you conclude about the sound you hear as the buzzer falls toward the ground? (a) (b) (c) (d)

The frequency and intensity increase. The frequency decreases and the intensity increases. The frequency decreases and the intensity decreases. The frequency remains the same, but the intensity decreases.

10. Which of the following frequencies are higher harmonics of a string with fundamental frequency of 150 Hz? (a) 200 Hz

(b) 300 Hz

(c) 400 Hz

(d) 500 Hz

(e) 600 Hz

11. A pipe open at both ends resonates at a fundamental frequency ฀฀open. When one end is covered and the pipe is again made to resonate, the fundamental frequency is ฀฀closed . Which of the following expressions describes how these two resonant frequencies compare? (a) ฀฀closed = ฀฀open (d) ฀฀closed =

3

(b) ฀฀closed = ฀฀open 2

1 ฀฀ 2 open

(c) ฀฀closed = 2฀฀open

(e) none of these

12. Which of the following statements is true about light waves? (a) The higher the frequency, the longer the wavelength. (b) The lower the frequency, the longer the wavelength. (c) Higher-frequency light travels faster than lower-frequency light. (d) The shorter the wavelength, the higher the frequency. (e) The lower the frequency, the shorter the wavelength.

End of Part A

Answers will be posted on the Structured Study Session web page: http://library.usask.ca/sss

4 Part B – Long Answer Questions B1. A 62.0-kg survivor of a cruise line disaster rests atop a block of Styrofoam insulation, using it as a raft. The Styrofoam has dimensions 2.00 m × 2.00 m × 0.0900 m. The bottom 0.024 m of the raft is submerged. (a) Draw a force diagram of the system consisting of the survivor and raft. (b) Write Newton’s second law for the system in one dimension, using ฀฀ for buoyancy, ฀฀ for the weight of the survivor, and ฀฀฀฀ for the weight of the raft. (c) Calculate the numeric value for the buoyancy, ฀฀. (Seawater has density 1025 kg/m3 .) (d) Using the value of ฀฀ and the weight of the survivor, calculate the weight ฀฀฀฀ of the Styrofoam. (e) What is the density of the Styrofoam? (f) What is the maximum buoyant force, corresponding to the raft being submerged up to its top surface?

Answers will be posted on the Structured Study Session web page: http://library.usask.ca/sss

5 B2. A 0.250-kg block attached to a light spring oscillates on a frictionless, horizontal table. The oscillation amplitude is ฀฀ = 0.125 m and the block moves at 3.00 m/s as it passes through equilibrium at ฀฀ = 0. (a) Find the spring constant, ฀฀. (b) Calculate the total energy of the block-spring system. (c) Find the block's speed when ฀฀ = ฀฀/2.

Answers will be posted on the Structured Study Session web page: http://library.usask.ca/sss

6 B3. An object executes simple harmonic motion with amplitude ฀฀. (a) At what values of its position does its speed equal half its maximum speed? (b) At what values of its position does its potential energy equal half the total energy?

Answers will be posted on the Structured Study Session web page: http://library.usask.ca/sss

7 B4. A yellow submarine travelling horizontally at 11.0 m/s uses sonar with a frequency of 5.27 × 103 Hz. A red submarine is in front of the yellow submarine and moving 3.00 m/s relative to the water in the same direction. A crew member in the red submarine observes sound waves (“pings”) from the yellow submarine. Take the speed of sound in seawater as 1533 m/s. (a) Which submarine is the source of the sound? (b) Which submarine carries the observer? (c) Does the motion of the observer’s submarine increase or decrease the time between the pressure maxima of the incoming sound waves? How does that affect the observed period? The observed frequency? (d) Should the sign of ฀฀0 be positive or negative? (e) Does the motion of the source submarine increase or decrease the time observed between the pressure maxima? How does this motion affect the observed period? The observed frequency? (f) What sign should be chosen for ฀฀฀฀ ? (g) Substitute the appropriate numbers and obtain the frequency observed by the crew member on the red submarine.

End of Part B

Answers will be posted on the Structured Study Session web page: http://library.usask.ca/sss

8 Want to help other students? Apply to be a PAL Peer Mentor for Fall 2018! We are recruiting volunteers for the Peer Assisted Learning (PAL) program for the 2018/2019 academic year. Develop your leadership, mentorship and presentation skills while assisting other students to be successful. We are seeking students who are: • • •

interested in sharing their own academic experiences in an interactive and informal setting; upper year students with a 75% average or higher; and who are available 5-10 hours/week depending on the volunteer role

Deadline to apply is Friday March 9th, 2018.

Need more information? Attend a 30-minute information session, led by a current peer mentor, or visit our website library.usask.ca/pal to learn more or apply. Questions? [email protected]

Information Sessions (30-minutes, in Murray Library) Tuesday February 13th, 11:30 am and 12:00 pm in room 102 Wednesday February 14th, 1:30 pm and 2:00 pm in room 102 Wednesday February 28th, 2:30 pm and 3:00 pm in room 102 Thursday March 1st, 11:30 am and 12:00 pm in room G3 Tuesday March 6th, 4:00 pm and 4:30 pm in room 102 Wednesday March 7th, 3:30 pm and 4:00 pm in room 102.

Answers will be posted on the Structured Study Session web page: http://library.usask.ca/sss...