Unformatted text preview: Physics 111
LAST name_!!!!!!!!!!!!!!! Sec: M1 M3 M53 M73 T83 T113 T2
First name____________________________________________(1 pt for legible name and correct section circled)
Seat number______________ T53 Exam 4
T73 Physics 111 Exam Instructions
•PLEASE WRITE YOUR NAME ON ALL PAGES OF THIS EXAM.
•No books, notes, headphones, earbuds, electronic devices, caps with bills, or sunglasses; calculators OK.
•Standards for academic integrity will be enforced as described in the syllabus.
•Be prepared to present your UMBC ID.
•For objective items (e.g., multiple choice, multiple answer, true/false, matching) no work required and no partial credit.
•For free-response items (e.g., calculate, determine, find, explain) show clear evidence of your reasoning process. A
correct response without supporting work will receive no credit. An incorrect response may receive partial credit on the basis
of clear, complete, and correct supporting work.
•Give numerical results to two significant figures with appropriate units. Complete the arithmetic for full credit. (1-4) Cylinder A contains Ne atoms (mass ~20 u) and cylinder B contains Ar atoms (mass ~40 u). The volume of cylinder A is 2 times the volume of cylinder B. Both cylinders are at the same temperature and pressure. (2 pts each) 1. The average kinetic energy of the Ne atoms is___________ the average kinetic energy of the Ar atoms. Ne
a. 4 times b. 2 times A
c. 2 times d. the same as 2. The average speed of the Ne atoms is___________ the average speed of the Ar atoms. a. 4 times b. 2 times c. 2 times d. the same as 3. Which has the greater number of atoms? a. the cylinder of Ne atoms b. the cylinder of Ar atoms c. both the same 4. Which has the greater thermal energy? a. the cylinder of Ne atoms b. the cylinder of Ar atoms c. both the same (5-6) (2 pts each) For the ideal gas process 1→2 depicted in the pV diagram at right, 5. the thermal energy of the system 6. …and heat flows a. increases a. from the surroundings to the system b. decreases b. from the system to the surroundings c. stays the same c. actually there’s no flow of heat in this process Name__________________________________ (7-8) An ideal gas in a cylinder expands. The cylinder is wellinsulated so that no heat flows between the surroundings and the gas. (2 pts each) 7. Which of the following is zero? a. The change in pressure of the gas b. The change in thermal energy of the gas c. The work that the surroundings do on the gas d. none of the above 8. If the initial state is 0 on the diagram at right, what’s the final state? 1 2 3 4 5 6 7 8 (9-12) A 4.0 kg block attached to a spring that has a spring constant of 25 N/m oscillates according to the x-t graph below. Position R is +2.0 m. (2 pts each) 9. What’s the magnitude and direction of the acceleration at time K? a. +50 m/s2 b. -50 m/s2 2
c. +13 m/s d. -13 m/s2 e. +8.0 m/s2 f. -8.0 m/s2 g. 0 10. What’s the magnitude and direction of the spring force at time L? a. +50 N b. -50 N c. +13 N d. -13 N e. +8.0 N f. -8.0 N g. 0 11. What’s the block’s velocity at time M? a. +5.0 m/s b. -5.0 m/s c. +2.5 m/s d. -2.5 m/s e. +0.80 m/s f. -0.80 m/s g. 0 12. What’s the time N? a. 25 s b. 5.0 s c. 2.5 s d. 0.80 s e. 0 Name__________________________________ 13. A cylinder contains 2.0 moles of a monatomic ideal gas at 400 K. (a-b) The gas is heated to 600 K at constant volume. a. Find the change in thermal energy of the gas. (3 b. How much heat is transferred to the gas? (2 pts) pts) (c-e) The gas is now returned to its original temperature of 400 K. This time, it’s heated to 600 K at constant pressure. c. Find the change in thermal d. How much heat is transferred e. How much work is done by the energy of the gas. (3 pts) to the gas? (2 pts) gas on the surroundings during this process? (3 pts) Name__________________________________ 14. A 0.50-kg block of ice originally at 0 °C is placed in thermal contact with a block of silver which is initially at 400 °C. The system reaches equilibrium at a temperature of 50 °C. The system is insulated so no heat flows into or out of it. Find the mass of the block of silver. Use cAg = 230 J/kg-K, cwater = 4200 J/kgK, and Lf = 3.3×105 J/kg. (7 pts) ...
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- Fall '14