phy2053, review - department of physicsphy2053, fall 2013, review, dec 1, 2013!! problem 12! two...

PHY2053, Review Dec 1st, 2013

PHY2053, Fall 2013, Review, Dec 1, 2013

Final Exam:��Sat, December 7, 12:30-2:30pm

Last Name Room Last Name Room A-E CLB C130 P-R WEIL 270 F-K MCCC 100 S-T LIT 101 L-O FLI 50 U-Z LIT 109

●  Crib sheet: You may bring two hand written formula sheet on 8½ x 11 inch paper (both sides).

●  Calculator: You should bring a calculator (any type). ●  Scratch Paper: We will provide scratch paper.


Distribution of Material Material # Problems

Your Exam 1 4 Your Exam 2 4

Chapter 10.5 – 12.8 6 Chapter 1.1 – 10.4 6


Make-Up Exam:��Wed, December 4, 5:10–7:00 pm For anyone who had to miss an exam during the semester. ●  E-mail to [email protected], state which exam

you are making up ●  Distribution of material: similar to that of final exam ●  Crib sheet: You may bring two hand written formula

sheet on 8½ x 11 inch paper (both sides). ●  Calculator: You should bring a calculator (any type). ●  Scratch Paper: We will provide scratch paper.

H-ITT Questions


Question 1 Online Graded Homework: Which of the following best expresses your opinion on the WebAssign online homework? A.  Very important part of the course. I learned a lot by doing

the homework and I think it should be graded. B.  I learned a lot from the homework, but I would have

preferred that it not be graded. C.  I learned a little bit by doing the homework and I think it

should be graded. D.  I learned a little bit by doing the homework, but I would

have preferred that it not be graded. E.  Complete waste of time. I learned nothing by doing the

homework.


Question 2 Quizzes: Which of the following best expresses your opinion on quizzes in the discussion sections? A.  Very important part of the course. I learned a lot by doing

the quizzes and I think the grading system was fair. B.  I learned a lot from the quizzes, but I would have preferred a

different grading system. C.  I learned a little bit by doing the quizzes and I think the

grading system was fair. D.  I learned a little bit by doing the quizzes, but I would have

preferred a different grading system. E.  Complete waste of time. I learned nothing by doing the

quizzes.


Question 3 The Lectures: Which of the following best expresses your opinion on the lectures (i.e.coming to class)? A.  Very important part of the course. I learned a lot from the

lectures and I enjoyed the HITT questions. B.  I learned a lot from the lectures, but I did not like the HITT

questions. C.  I learned a little from the lectures and the HITT questions. D.  I learned a little from the lectures, but I did not like the HITT

questions. E.  Complete waste of time. I learned nothing by coming to

class.


Question 4 Overall Course: Which of the following best expresses your opinion on what you learned from the course? A.  I enjoyed the course, and I learned a lot by taking this

course. B.  I did not enjoy the course, but I learned a lot by taking this

course. C.  I enjoyed the course, and I learned a little bit by taking this

course. D.  I did not enjoy the course, but I learned a little bit by taking

this course. E.  Complete waste of time. I learned nothing from this course.

Review: Problems


Problem 1 The keys A4 and B4 on a piano correspond to frequencies of 440 Hz and 493 Hz, respectively. If these two keys are played together, what is the beat frequency of the resulting wave (in Hz)? Answer: 53 Hz

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Problem 2 At what height above the Earth’s surface would your weight be 1/4 of what it is at the surface of the Earth? (Note: RE is the radius of the Earth.) Answer: RE


Problem 3 Near the surface of the Earth, a cloth tape is wound around the outside of the two uniform solid cylinders shown in the figure. Solid cylinder 1 has mass M1, radius R1, and moment of inertia I1 =½M1R1

2. Solid cylinder 2 has mass M2, radius R2, and moment of inertia I2 =½M2R2

2. Cylinder 2 is attached to the ceiling and rotates without friction, and cylinder 1 hangs vertically. If M1 = fM2, when the cylinders are released from rest and the tape unwinds off both cylinders, what is the acceleration of the center-of-mass of cylinder 1 (in m/s2)?


Problem 4 The escape speed from the surface of a planet is the minimal initial speed a projectile must have to escape the gravitational pull of the planet. For Earth, the escape speed is about 11.2 km/s. What is the escape speed (in km/s) from a planet that has twice the mass of the Earth and one-half the radius of the Earth? Answer: 22.4 km/s


Problem 5 The coefficient of static friction between a certain cylinder with radius R and a horizontal floor is μs. If the rotational inertia of the cylinder about its symmetry axis is given by I = MR2/2 and the magnitude of the maximum translational acceleration the cylinder can have without sliding is 7.84 m/s2, what is μs? Answer: μs = 0.4


Problem 6 Two small balls are simultaneously released from rest in a deep pool of water (with density ρwater). The first ball is released from rest at the surface of the pool and has a density 1.5 times the density of water (i.e. ρ1 = 1.5ρwater). A second ball of unknown density is released from rest at the bottom of the pool. If it takes the second ball the same amount of time to reach the surface of the pool as it takes for the first ball to reach the bottom of the pool, what is the density of the second ball? Neglect hydrodynamic drag forces.


Problem 7 Use Bernoulli’s equation to estimate the upward force (in kN) on an airplane’s wing if the average flow speed of the air is 200 m/s above the wing and 175 m/s below the wing. The density of air is 1.3 kg/m3 and the area of each wing surface is 30 m2. Answer: 183 kN


Problem 8 A simple harmonic oscillator consists of a block of mass 2 kg attached to an ideal spring with spring constant k. If the speed of the block is 20 m/s when the displacement from equilibrium is 3 m and the amplitude of the oscillations is 5 m, what is the spring constant k (in N/m)? Answer: 50 N/m


Problem 9 A 2,000 kg wrecking ball is to be lifted by a crane with a steel cable that has a diameter of 2.0 cm and an unstretched length of 31.4 m. The Young’s modulus of steel is 2.0 × 1011Pa. Ignoring the weight of the cable itself, when the ball is lifted and held at rest how much does the cable stretch (in cm)? Answer: 0.98 cm


Problem 10 A dangerous highway curve has a radius R = 200 m is banked in the wrong direction θ = 10º as shown in the figure. If the static coefficient of friction between the car and the highway is 0.4, what is the maximum speed the car can travel around the curve without slipping (in m/s)? Answer: 20.2 m/s


Problem 11 A stationary motion detector sends sound waves of frequency of 500 Hz toward an approaching truck. The waves sent out by the detector are reflected off the truck and then are received back at the detector. If the frequency of the waves received back at the detector is 700 Hz, what is the speed of the approaching truck (in m/s)? (Take the speed of sound to be 343 m/s.) Answer: 57.2 m/s


Problem 12 Two traveling pressure waves (wave A and wave B) have the same frequency and wavelength. The waves are superimposed upon each other. The amplitude of the resulting wave (wave C) is 17 kPa. If the amplitude of wave A is 15 kPa and the phase difference between wave B and wave A is φB − φA = 90º, what is the amplitude of wave B and the magnitude of the phase difference between wave A and wave C, respectively? Answer: 8 kPa, 28.07º


Problem 13 Two point masses are located on the x-axis. Mass m1 is at the origin (i.e., x = 0) and mass m2 is at x = d. If m2 = 2m1, at what point on the x-axis is the net gravitational force on a test mass m from the two masses equal to zero? Answer: x = 0.41 d


Problem 14 Near the surface of the earth, a conical pendulum is constructed from a stone of mass M connected to a cord with length L and negligible mass. The stone is undergoing uniform circular motion in the horizontal plane as shown in the figure. If the cord makes an angle φ = 40◦ with the vertical direction and the period of the circular motion is 3 s, what is the length L of the cord (in meters)? Answer: 2.92 m


Problem 15 A beanbag is thrown horizontally from a dorm room window a height h above the ground. It hits the ground a horizontal distance d = 3h from the dorm directly below the window from which it was thrown. Ignoring air resistance, find the direction of the beanbag’s velocity just before impact. Answer: 33.7º below the horizontal


Problem 16 A person with a mass of 100 kg stands on one end of a 20-m long raft. The mass of the raft is 300 kg, and the other end of the raft is 1 m away from the shore. The person runs as fast as they can, 10 m/s with respect to the raft. At the end of the raft, the person jumps upward. In the jump, the magnitude of the person’s velocity with respect to ground will stay the same, only its direction will change. Where will the person land – on ground or in the water?

phy2053, review - department of physicsphy2053, fall 2013, review, dec 1, 2013!! problem 12! two...

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