PHYS 1401 General Physics I Test 3 Review Questions

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1 PHYS 1401 General Physics I Tes 3 Review Quesions Ch A 6500 kg railroad car moving a 4.0 m/s couples wih a second 7500 kg car iniially a res. a) Skech before and afer picures of he siuaion. b) Wha assumpions do you need o make so ha conservaion of momenum holds? c) Find he final velociy of boh cars. d) Find he raio of final o iniial kineic energy? Explain why his raio should be less han 1. e) Wha is he change in momenum of he second car? f) If he collision lased for 0.2 s, wha is he average force exered on he second car? g) How does i compare o he average force exered on he firs car. Explain your answer. 2. A 15.0 g bulle srikes and becomes embedded in a 1.10 kg block of wood placed on a horizonal surface jus in fron of he gun. If he coefficien of kineic fricion beween he block and he surface is.250 and he impac drives he block a disance of 9.50 m before i comes o res, wha was he iniial speed of he bulle? 3. A small car of mass 125 g is raveling wes a 2.0 m/s. I is apped by a hammer and ends up raveling wes a 3.0 m/s. a) If he lengh of he ap was.20 s, find he average force exered on he car. b) On he axes below skech graphs of he force vs. ime and velociy vs. ime. Use he same ime scale for boh. Force ime V ime 4. A 130 kg person is raveling wes a 1.5 m/s. A gus of wind from he wes pushes on he person bringing him o a sop in.75 s. a) Skech he siuaion. b) Deermine he change in momenum of he person. c) Deermine he average force acing on he person. d) Skech graphs of he person s velociy versus ime and he force vs. ime acing on he person.

2 5. a) Skech a possible velociy vs. ime graph for he following impulse. F v b) Skech a force vs. ime graph for he following velociy graph. F v 6. A red car of mass 1200 kg iniially ravels eas a 20 m/s and a blue car of mass 1400 kg iniially ravels wes a 5 m/s. The cars collide and lock ogeher. a) Wha ype of collision is his? b) Wha assumpions do you need o make so ha conservaion of momenum can be used o solve his problem? c) Is kineic energy conserved in his problem? Explain. d) Draw before and afer picures of he collision. e) Find he velociies of he cars direcly afer he collision. 7. a) Wrie a problem corresponding o he following equaion. (1200 kg) (14 m/s) + (1100 kg) (10 m/s) = (2300 kg) v f b) Skech before and afer picures corresponding o your problem. c) Solve he problem you have wrien. 8. A firecracker is iniially a res. Jus afer i blows up, i splis ino hree pieces. One piece of ¼ he mass of he firecracker ravels horizonally a 15 m/s. A second piece of ¼ of he firecracker ravels sraigh up a 12 m/s. a) Skech before and afer picures of he explosion. b) Is i reasonable o ignore exernal forces during he explosion? Explain. c) Wha conservaion law applies here? d) Find he speed and direcion of he hird piece of firecracker jus afer he explosion.

3 9. A billiard ball wih mass 75 g iniially raveling a 2.0 m/s collides elasically wih an idenical ball iniially a res. a) Skech before and afer picures for he collision. b) Wha conservaion laws apply o his collision? Explain. c) Wrie he equaions given by he conservaion laws for his problem. d) Find he speed of boh balls afer he collision. Ch A balmy spring day has a emperaure of 80 F. a) Conver ha emperaure o celsius and kelvin. b) Wha change is here o he kineic energy of he gas as he amosphere cools off o 40 F ha nigh? 11. A 10 m long seel beam is a a emperaure of 10 C. a) Skech he siuaion and indicae he change of lengh. b) How much will he beam change in lengh if i is cooled o -10 C? 12. A conainer conains 2.5 l of waer a 20 C. The conainer is heaed o a emperaure of 25 C. a) By how much does he volume of he waer change? b) If he average global emperaure increased, wha effec would his have on he volume of waer in he ocean. 13. A consan volume ideal gas hermomeer is immersed in a waer bah a a emperaure of 37 C. The hermomeer is hen immersed in a bah a a differen pressure and he measured pressure doubles. a) Skech he siuaion. Is he second bah a a higher or lower emperaure han 37 C? Explain. Find he emperaure of he second bah. Ch A suden makes he following saemen abou wo idenical blocks of meal a differen emperaures: The block a he higher emperaure has more hea, han he block a he lower emperaure. There is somehing wrong wih he suden s saemen. a) Describe wha is wrong. b) Explain your answer. 15. A closed conainer wih 150 g of seam is iniially a a emperaure of C. The conainer is placed ino a freezer unil all of he seam is convered o ice a 0.0 C. a) Skech he siuaion. b) Describe he flow of hea in his process. c) Draw a heaing curve for he process, only. Do no include pars on he heaing curve which did no occur in he described process. d) Find he oal amoun of energy ha mus be added or removed o carry ou his process. 16. A 150 block of ice is iniially a 10 C. Hea is added a a consan rae unil evenually seam a 110 C is produced. a) Draw a heaing curve for he process. b) Assuming no hea is los o he environmen, find he oal hea added. 17. A ub iniially conains 5.0 kg of cold waer a 23 C. A ho waer ap is opened and 3.0 kg of waer a 65 C is added. a) Skech he siuaion. b) Describe he flow of hea in his process. c) Find he final emperaure of he waer. d) Did he average kineic energy of he cold waer or he ho waer change more? Carefully explain your answer.

4 g of a subsance is heaed o 330 C and hen plunged ino an insulaing conainer holding 250 g of waer a a emperaure of 18 C. If he final observed emperaure is 38 C, wha is he specific hea of he subsance? (c = 1 cal/(g C) = 4186 J/(kg C) for waer) 19. The red gian sar Beelgeuse has a radius of r = 3.1 x m. Is surface emperaure is 2800 K. Assuming i is a perfec emier e = 1, wha is he power oupu of he sar. (Hin: A = 4πr 2 ) 20. Describe he differences beween conducion and convecion. 21. Why is he inside surface of a hermos bole silvered? 22. Wha hea ransfer mechanism(s) are you rying o foil when you cover a ho lasagna wih aluminum foil? 23. Would i be cheaper o cool a house on a ho summer day if he house was pained black or if i was pained whie? Explain your answer. b) Would i be cheaper o hea a house on a cold winer day if he house was pained black or if i was pained whie? Explain your answer. 24. A house has a single pane glass window wih a hickness of 5.0 mm and dimensions 65 cm x 98 cm. I is a brually ho summer day wih an ouside emperaure of 104 F. Inside he house is mainained a 78 F. a) Skech he siuaion. b) Describe he direcion of energy ransfer for his siuaion. c) Find he oal amoun of energy ransferred hrough he window in 1 hour. Ch The PV diagram for a cyclic process is shown below. The process begins and ends a he poin indicaed by he black do. a) Find he change in inernal energy. b) Find he work done on he sysem. c) Find he energy added or removed by hea in his process. PV Diagram 2.5 Pressure (am) Volume (liers)

5 P (am) 26. In a process 250 J of work are done on an ideal gas and 100 J of energy is ransferred ou of he sysem by hea. a) Skech he siuaion. b) Find he change in inernal energy of he gas. c) Did he emperaure of he gas increase, decrease or remain he same? Explain your answer. 27. A hea engine uses a closed cycle. 575 J of hea are added per cycle. If he engine is 25% efficien, find he ne work done in each cycle, and he hea wased in each cycle. 28. A pison conains.020 m 3 of an ideal gas a pressure of 1 am and a emperaure of 20 C. Hea energy is added isohermally so ha he volume of he pison doubles. a) Skech he siuaion. b) Draw a PV diagram for he process. c) How much work is done by he pison? d) Wha is he change in inernal energy of he gas? e) How much hea was added? 29. An ideal gas has is pressure cu in half slowly, while being kep in a conainer wih rigid walls. 265 kj of hea lef he gas during he process. a) Wha variable will remain consan? b) How much work is done in he process? c) Wha is he change in inernal energy of he gas? 30. An ideal gas is adiabaically compressed by a process which does 300 J of work on he sysem. a) How much hea was given off? b) Wha was he change in inernal energy of he gas? c) Wha happened o he emperaure of he gas? Explain. 31. For he process shown in he figure below, a) idenify each leg of he process as isohermal, isochoric, isobaric, or adiabaic. b) Assuming he process proceeds in a clockwise fashion, find he work done on he sysem, he change in inernal energy of he sysem, and he hea added or removed for one cycle. PV Diagram V (lier)

Activity 4 Solutions: Transfer of Thermal Energy

Activity 4 Solutions: Transfer of Thermal Energy Aciviy 4 Soluions: Transfer of Thermal nergy 4.1 How Does Temperaure Differ from Thermal nergy? a) Temperaure Your insrucor will demonsrae molecular moion a differen emperaures. 1) Wha happens o molecular