PHYSICS I1 EXAM 3 FALL 2005

Transcription

1 PHYSCS 1 EXAM 3 FALL A 0.02 kg mass is attached to a massless spring as shown to the right and vibrates with simple harmonic motion with an amplitude of 5.0 cm. The spring constant is 300 Nlm. What is the speed of the mass when it is 2.0 cm from its equilibrium position? (a) 2.1 rnls (b) 3.2 rnls (c) ml$ (e) 6.8 rnls 38. A 2.0 kg mass on the end of a horizontal spring is vibrating with simple harmonic motion and can be described by the equation x = 0.3 cos (5.0 t). What is the period of the vibration? (a) 0.3 s@) 1.3 s>(c) 2.8 s (d) 4.2 s (e) 5.0 s 39. A plot of height vs time for a sinusoidal sound wave traveling in air is shown in the figure to the right. What is the wavelength of this wave? (a) 14 cm (b) 18 cm (d) 34 cm (e) 40 cm

2 40. Sound waves are and generally travel - as the density of the medium through which the sound wave travels increases. (a) transverse, faster 1 longitudinal, fast9 (c) transverse, slower longitudinal, slower 41. A guitar string has a length of 80 cm and a mass of 5.0 grams. The player tunes the string so that the second harmonic produces sound with a frequency of 600 Hz. What is the required tension in that guitar string? (b) 1.03~1 o3 N (c) 1.25~1 o3 N (e) 2.06~1 o3 N 42. n a demonstration the lecturer swung a length of plastic pipe that was open at both ends. The students heard - (a) (b) (c) essentially no sound only a swishing noise as the pipe swung through the air a sound of uniform pitch from a standing sound wave set up in the pipe similar to (c) but the pitch decreased as the pipe swung towards the students. similar to (c) but the pitch increased as the pipe swung towards the students. 43. An organ pipe closed at one end is sounding its third harmonic at a frequency of 900 Hz. How long is the pipe? (a) 9.5 cm (b) 19 cm&z9%(d) 38 cm (e) the third harmonic does not exist for closed pipes.

3 44. As you wait at a railroad crossing an approaching train blows its whistle. At that moment the engineer in the train hears a whistle frequency of 800 Hz while you hear a frequency of 900 Hz. What is the speed of the approaching train? (a) 28 mls (b) 32 m/s ( z m 3 (d) 43 m/s (e) 46 m/s 45. A flat iece of wood of density 0.80~1 o3 kg/m3 and volume 2.0 m P is floating in a lake. What mass of iron must be placed on top to just submerge the log? (b) 800 kg (c) 1200 kg (d) 1600 kg (e) 2000 kg 46. A piece of iron is thrown into a bucket of water. After the iron is completely submerged, it sinks to the bottom of the bucket and. (d) (e) no buoyant force acts on it the buoyant force is approximately constant with depth the buoyant force increases with depth the buoyant force decreases with depth the buoyant force becomes zero after the iron hits the bottom 47..Bernoulli's equation is a statement of conservation of for fluids of constant density. Gsa(b) momentum (c) angular momentum (d) mass (e) pressure

4 .8. Water is flowing in a cylindrical pipe & as shown in the figure to the right. - f the pressure and velocity of the water at point 1 are 6 kpa and t m/s, respectively, what is the so - pressure at point 2. Hint: First determine the velocity at point (b) 1.8 kpa (c) 2.8 kpa (d) 4.4 kpa (e) 6.0 kpa 49. A pitcher throws a baseball and causes it to spin as shown in the figure to the right. The view is of a person whose eyes are at the same vertical level as the ball. ' 6ROUND neglecting the effects of gravity the ball will - (a) curve to the right (b) curve to the curve up relative to the ground (rise) (d) curve down relative to the ground (drop) (e) not curve at 50. At what temperature is the value on the Fahrenheit and Celsius scales the same? (this is the easy one) (a) -10" (b) -20" (c) -30" (e) -50"

5 51. A thin circular plate of copper has a diameter of 0.60 m at room temperature (20 c). By how much does the area increase if it is heated to 50 c? (b) 1.8~10- m (c) 2.3~10 m -3 2 (e) 3.4~10 m 52. A childs balloon is filled with He gas at room temperature (20 c) until its total volume is 1500 cm3. How many He atoms are in the balloon? a) 1.1~122 (b) 1.8~10~~ (c) 2.4~10~~ (d) 3.3~10" &+ij-ml& 53. Nitrogen (N2) molecules in a region of Antarctica are measured to have a RMS velocity of 420 mls. What is temperature at this place in Antarctica? The atomic mass of a nitrogen atom is 14 gramslmole. (a) OOc (b) -28'~ (c) -40c (d) -630cGP5-54. An astronaut visits the moon on the side that always faces the sun, with an ice cube at -loc in a sealed container. During the moon walk he opens the container and the ice cube -. Assume container at -0c o. 0 ~ when he opens it. (a) (b) & (e) remains solid ice melts and remains liquid melts and then vaporizes changes directly from ice to water vapor depends on the temperature at the moon's surface