A hockey puck traveling at speed v on essentially frictionless ice collides elastically with one end of a straight stick lying flat on the ice. In this collision
a. momentum is conserved. b. angular momentum is conserved. c. energy is conserved. d. all of the above are conserved. e. only momentum and angular momentum are conserved.
D
You might also like to view...
A circular current loop with radius r has a magnetic dipole moment ?. To gain the greatest increase in its magnitude, you could
1.double the radius and maintain the current. 2.double the radius and halve the current. 3.halve the radius and double the current. 4.double the current and maintain the radius.
The sunspot cycle affects I. the latitude at which sunspots are visible at a given time. II. the number of sunspots that are visible at a given time. III. the rotation rate of the Sun's equator at a given time. IV. the magnetic polarity of the sunspots at a given time
a. I & II b. I & IV c. II & III d. I, II & III e. I, II, & IV
Two concentric spheres 0.2 m and 0.3-m in diameter, with the space between them evacuated, are to be used to store liquid air (133 K). If the surfaces of the spheres have been flashed with aluminum and the liquid air has a talent heat of vaporization of 209 kJ/kg, determine the number of kilograms of liquid air evaporated per hour.
GIVEN
• Two concentric spheres with the space between them evacuated and liquid air in the inner sphere
• Diameters ? D1 = 0.2 m ? D2 = 0.3 m
• Liquid air temperature (Ta) = 133 K
• Room temperature (T?) = 293 K
• Surfaces of the spheres have been flashed with aluminum
• Heat of vaporization of liquid air (hfg) = 209 kJ/kg = 209,000 J/kg
FIND
• The number of kilograms of liquid air evaporated per hour ( )m
ASSUMPTIONS
• Steady state
• Convective thermal resistance between the liquid air and interior sphere is negligible
• Thermal resistance of the sphere walls is negligible
• Natural convection on the exterior is negligible
• The room behaves as a blackbody enclosure
• The thickness of the sphere walls in negligible
SKETCH
PROPERTIES AND CONSTANTS
the Stephan-Boltzmann constant (?) = 5.67 × 10–8 W/(m2 K4)
the hemispherical emissivity of the spheres will be approximated by that for oxidized aluminum at 310 K: ? = ?1 ? 2 = 0.11
____________________ is the resistance of a gas to the flow of radiation
Fill in the blank(s) with correct word