Elementary Physics November 16, 2015

Size: px

Start display at page:

Download "Elementary Physics November 16, 2015"

Bartholomew Page
7 years ago
Views:

1 Circle your Recitation: A01 A03 A04 A08 A05 A06 A07 A02 Myers Yang Pepe Myers Pepe Sanders Sanders Yang (8:30 a.m.) (11:40 a.m.) (1:15 p.m.) (1:15 p.m.) (2:50 p.m.) (4:25 p.m.) (6:00 p.m.) (7:35 p.m.) INSTRUCTIONS: For the multiple choice questions on pages 1 2, you will be graded on the basis of your answer only. You will get full credit for a correct answer, zero credit for incorrect answers, zero credit for choosing multiple answers even if one of them is the correct response. There is only one correct answer for each multiple choice question. For the problems on pages 3 5, you must show your work in the form of a diagram, statement and/or equation to get full credit, even if you write down the correct answer. If your answer is incorrect, you will receive partial credit for steps taken in the direction of the correct solution. So, show all your work. No books or notes are permitted in this examination. Writing instruments and a calculator are the only items that you will need. ** READ THE QUESTIONS CAREFULLY ** SCORE BOX Page 1 (8) Page 2 (16) Page 3 (14) Page 4 (14) Page 5 (12) Total (64) 1. A gas is compressed by an isothermal process that decreases its volume by a factor of 2. In this process, the pressure (a) increases by a factor of 2. (b) increases by a factor of more than 2. (c) does not change. (d) increases by a factor of less than A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper, with the aluminum and the copper in thermal contact. The specific heat capacity of aluminum is more than double that of copper. Which object experiences the greater temperature change during the time the system takes to reach thermal equilibrium? (a) Neither one; both of them experience the same size temperature change. (b) It is impossible to tell without knowing the masses. (c) It is impossible to tell without knowing the volumes. (d) the copper (e) the aluminum αβγδ p. 1 page total:

2 3. A 10 kg pail of water is lowered by a rope, starting from rest. When it has descended a distance of 5.0 m, it has a speed of 5.0 m/s. How much work was done on the pail of water by the rope over this distance? (a) - 96 J (b) J (c) J (d) J (e) -463 J 4. A boy throws three identical balls off a cliff, each with the same launch speed, but with different launch angles. If air resistance is negligible, which ball hits the ground with the greatest speed? (a) A (b) B (c) C (d) They all have the same final speed. 5. Two objects constitute an isolated system. In an elastic collision between the two objects, which one of the following statements is a false statement? (a) The magnitude of the force exerted by each object on the other object is equal. (b) The total kinetic energy is conserved. (c) The kinetic energy of each object is the same before and after the collision. (d) The total momentum is conserved. (e) The total kinetic energy before the collision is equal to the total kinetic energy after the collision. 6. A gas is taken through the cycle shown in the pv diagram in the figure. During one cycle, how much work is done by the gas? (a) p 0 V 0 (b) 2p 0 V 0 (c) 3p 0 V 0 (d) 4p 0 V 0 (e) No work is done because it s a closed cycle. αβγδ p. 2 page total:

3 7. A vendor hangs an 9.5 kg sign in front of his shop with a cable held away from the building by a 3.6 kg uniform pole. The pole is free to pivot about the end where it touches the wall, as shown in the drawing. Draw a freebody diagram for the pole and find (a) the magnitude of the tension in the cable and (b) the magnitudes of the horizontal and vertical components of the force that the wall exerts on the left end of the pole. αβγδ p. 3 page total:

4 8. Suppose you take and hold a deep breath on a chilly day, inhaling 2.5 L of air at 1.5 C. Assume that air pressure is 1.0 atm. (a) How much heat must your body supply to warm the air to your internal body temperature of 37 C? Assume that for air C p = 29.1 J/(K mol) as it consists mostly of nitrogen and oxygen. (b) How much does the volume of the air increase as it is warmed? αβγδ p. 4 page total:

5 9. Two hunks of clay slide on a frictionless surface as shown in the figure. Initially the 3.0 kg mass slides along the x-axis at 1.5 m/s and the 2.0 kg mass travels at 3.0 m/s in the +y direction. The two hunks of clay stick together at the origin, then slide away as one. With what speed, and in what direction do the hunks of clay move after sticking together? [Hint: What s the velocity of the center of mass?] 3.0 kg 1.5 m/s 5.0 kg v 3.0 m/s 2.0 kg (12) αβγδ p. 5 page total:

Physics 125 Practice Exam #3 Chapters 6-7 Professor Siegel

Physics 125 Practice Exam #3 Chapters 6-7 Professor Siegel Name: Lab Day: 1. A concrete block is pulled 7.0 m across a frictionless surface by means of a rope. The tension in the rope is 40 N; and the