Department of Natural Sciences Clayton State University. Physics 3650 Quiz 1. c. Both kinetic and elastic potential energies can be negative.

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1 Department of Natural Sienes Physis 3650 Quiz 1 August 5, Whih one of the statements below is orret? a. Elasti potential energy an be negative but the kineti energy annot. b. Kineti energy an be negative but the elasti potential energy annot.. Both kineti and elasti potential energies an be negative. d. Neither kineti nor elasti potential energy an be negative.. An eletron (a negative partile) is moving parallel to the diretion of the magneti field. The magneti fore on the eletron is a. Parallel to the diretion of magneti field. b. Anti-parallel to the diretion of magneti field.. Perpendiular to the diretion of magneti field. d. Zero. 3. A partile is moving westward. Diretion of the partile s linear momentum is a. North. b. South.. East. d. West. Department of Natural Sienes

2 Physis 3650 Quiz 1 September 5, 008 An unstable partile is reated in the upper atmosphere from a osmi ray and travels down toward the surfae of the Earth with a speed of relative to the Earth. A sientist at rest on the Earth s surfae measures that the partile is reated at an altitude of 45.0 km. a. As measured by a sientist, how muh time does it take the partile to travel the 45.0 km to the surfae of the Earth? L 0 t m t ( )( m / s) 4 s b. How far does the surfae of the Earth travels during this time from the partile s point of view? L L 0 1 ( ) L ( m) m. In the partile s referene frame, how muh time does it take the surfae to travel that distane? t 0 t 1

3 4 ( ) t0 ( s) s d. Whih one of the distanes mentioned above is a proper distane? Whih one of the rimes is the proper time? Sientist measures the proper distane (45,000 m), Partile measures the proper time (1.44 x 10-5 s) Physis 3650 Quiz 3 Name SOLUTION An imperial spaeship, moving at high speed relative to the planet Arrakis, fires a roket toward the planet with a speed of 0.90 relative to the spaeship. An observer on Arrakis measures that the roket is approahing with a speed of RS = 0.90 RA = SA =? a. What is the speed of spaeship relative to Arrakis? SA SR 1 RA SR RA SA ( 0.90) (0.360) 1 b. Is the spaeship moving toward or away from Arrakis? Away. Department of Natural Sienes

4 Physis 3650 Quiz 5 Otober 6, 008 Name _SOLUTION 1. Determine the wavelength of the seond Balmer line (n =4 to n transition). 1/= R (1/n 1/n ) = (1.10 x 10 7 m -1 ) (1// 1/4 ) = x 10 7 m -1 = 4.85 x 10-7 m = 485 nm. What are the shortest and the longest wavelengths in the Lyman (n = 1) series? Shortest: 1/= R (1/n 1/n ) = (1.10 x 10 7 m -1 ) (1//1 1/ ) = 1.10 x 10 7 m -1 = x 10-7 m = 90.9 nm Longest: 1/= R (1/n 1/n ) = (1.10 x 10 7 m -1 ) (1//1 1/ ) = 0.85 x 10 7 m -1 = 1.1 x 10-7 m = 11 nm Department of Natural Sienes Physis 3650 Quiz 6 Otober 15, 008 A hydrogen atom is in its fourth exited state aording to the Borh model (n = 5). a. What is the radius of the Bohr orbit? r n = n r 1

5 r 5 = (5) (0.059 nm) = 1.3 nm L n = n h/() b. What is the angular momentum of the eletron? L 5 =5 h/() = 5.8 x J-s. What is the eletron s kineti energy? L = p r p = L/r = 4.00 x 10-5 kg-m/s K = p /(m e ) = (4.00 x 10-5 kg-m/s) /((9.11 x kg)) = 8.78 x 10-0 J = e U = - k e /r d. What is the eletron s potential energy? U = - (8.99 x 10 9 N-m /kg ) (1.60 x C) /(1.3 x 10-9 m) = x 10-0 J = e E = K + U = e e. What is the eletron s total energy? Chek: E = (-13.6 e)/ n = e Department of Natural Sienes Physis 3650 Quiz 8 November 7, The most ommon kind of iron nuleus has a mass number of 56. Find the radius and approximate mass of the nuleus.

6 R = (1.0 x m)(56) 1/3 = 4.58 x m = 4.58 fermi M = 56 u 05. How many protons and how many neutrons are there in a nuleus of 81 Tl? A = Z + N = 05 Z = 81 Protons: 81 Neutrons: 14 Department of Natural Sienes Physis 3650 Quiz 9 November 14, 008 Name _SOLUTION 1. A radioative isotope whih emits an alpha partile will hange in what respet? a. Atomi number dereases by four. b. Mass number dereases by four.. Both hoies a and b are valid. d. None of the above hoies are valid.. If there are 18 neutrons in Pb-10, how many neutrons are in the nuleus of Pb-06? a. 1. b d What partile is emitted when P-3 deays into S-3? (Atomi numbers of P and S are, respetively, 15, and 16.)

7 a. Alpha. b. Beta.. Positron. d. Gamma photon.

( x vt) m (0.80)(3 10 m/s)( s) 1200 m m/s m/s m s 330 s c. 3.

( x vt) m (0.80)(3 10 m/s)( s) 1200 m m/s m/s m s 330 s c. 3. Solutions to HW 10 Problems and Exerises: 37.. Visualize: At t t t 0 s, the origins of the S, S, and S referene frames oinide. Solve: We have 1 ( v/ ) 1 (0.0) 1.667. (a) Using the Lorentz transformations,