PSCI 1055 Test #2 (Form A) Spring 2008 Buckley

Transcription

1 Name PSI 1055 Tet #2 (Form A) Spring 200 Buckley 1. (10 point) Since we deal a lot with unit, let ee how well you can match up the quantitie on the left with the lettered choice of unit on the right. The lettered choice may be ued more than once on the left, but only one choice hould be placed on each line. D frequency A. kelvin power B. meter G gravitational potential energy. watt B wavelength D. Hertz G work E. m/ H period E wavepeed G kinetic energy F. decibel G. Joule H. econd F loudne A abolute temperature 2. (4 point) Show your work. a. A 1000-kg car i traveling at a peed of 25 m/. What i it kinetic energy? Kinetic energy = ½ mv 2 = ½ (1000-kg)(25 m/) 2 = J b. How much work would be required to bring the car of part a to a complete top? Work would be equal to the kinetic energy = J c. If the kinetic energy of the car change to J, what i it new peed? J m m 1000kg 2 KE = mv J = (1000 kg) v v = = 300 v = 300 = 17 m / Page 1 of 6

2 3. (10 point) Show your work. a. A 25.0 kg ball i held at a height of 20.0 m above the floor. Uing the floor a the zero reference for height, what i the gravitational potential energy of the ball? Gravitational potential energy = mgh = (25.0 kg)(9. m/ 2 )(20.0 m) = 4900 J b. If the ball i dropped from the height of 20.0 m, what i it gravitational potential energy at a height of 10.0 m? Thi i halfway down, o half of the gravitational potential energy ha been converted to kinetic energy. Thi mean the gravitational potential energy i equal to ½ of 4900 J = 2450 J. c. What i the ball kinetic energy at the height of 10.0 m after being dropped from a height of 20.0 m? Halfway down, the kinetic energy matche the potential energy 2450 J. d. How fat i the ball traveling at the height of 10.0 m after being dropped from a height of 20.0 m? e. How much work would be required to raie the ball from a height of 20.0 m to a height of 30.0 m? J m m 25.0kg 2 KE = mv 2450 J = (25.0 kg) v v = = 196 v = 196 = 14 m / 4. (4 point) Make the following temperature converion. Show your work. a. 392 F = 5 5 = ( F 32) = (392 F 32) = b. 31 K = F K = o convert K to firt = K 273 = 31K 273 = F= + 32 = (45 ) + 32 = 113 F 5 5 Page 2 of 6

3 5. (6 point) Show your work. a. A hot pack can ometime be ued in athletic ituation where heat i needed to treat an injury on the field. Suppoe a hot pack contain eentially 250 g of water, the pecific heat of which i 416 J/kg-. If the reaction that occur in the hot pack produce J, how much doe the temperature rie in the hot pack? H 32000J H = m c T T = = = 30.6 m c 0.250kg 416 J / kg b. Sometime when there i a freeze threat in a citru grove, worker will pray water over the fruit. Thi ha two effect, one of which i that when the water freeze around the fruit it releae heat which then warm the fruit. Suppoe kg of water freeze around an orange. How much heat would thi amount of water releae to the orange? The latent heat of fuion of water i 0 kcal/kg. H = m H L = kg H 0 kcal/kg = 2.0 kcal c. If the orange in part b ha a ma of kg and a pecific heat of 0.60 kcal/kg-, by how much would the temperature of the orange increae due to the freezing of the water if all of the heat goe into the orange? H 2.0kcal H = m c T T = = = 22.2 m c 0.150kg 0.60 kcal / kg 6. (2 point) a. Give an example of a longitudinal wave. Sound b. Give an example of a tranvere wave. Light, wave on a rope Page 3 of 6

4 7. (6 point) Show your work. a. A ound wave ha a peed of 340 m/ and a frequency of 15 khz. Find it wavelength. c 340 m/ 2 c = λν λ = = = m ν Hz b. Red light ha a wavelength on the order of 7 H 10-7 m. What i the frequency of light with that wavelength? 3 10 / c m c = λν ν = = = λ 7 10 m 14 1 c. The period of a wave i 15. What i it frequency? f 1 1 = = = T (2 point) ircle the color of light with the larget frequency in each cae below. a. orange or yellow b. violet or red 9. (2 point) A ubway train generate a ound on the order of 90 decibel. ity traffic generate ound of about 70 decibel. By what factor i a ubway train louder than city traffic? Two decade of difference = 10 2 = 100 time louder 10. (2 point) The index of refraction of light in diamond i What i the peed of light in diamond? c c 3 10 m/ n = ncm = c cm = = = m / c n 2.42 m 11. (4 point) For each of the diagram below, identify each image a a concave mirror, a convex mirror, a convex len, or a concave len. oncave mirror oncave len onvex len onvex mirror Page 4 of 6

5 12. ( point) omplete the following ketch to anwer the quetion about the image formed by the convex mirror. ircle the correct choice. a. The image i: real or virtual b. The image i: upright or inverted c. The image i: larger than or maller than the object. f Page 5 of 6

6 1 = mv = mgh 2 2 W=Fd E k E p W 9 P= TK = T TF = T + 32 t 5 T 5 = ( TF 32) H = m c T H = m L 9 1 f = v = T λ T v = fλ c = m/ n = c c m Page 6 of 6