Any change of the energy of a system occurs because of
a. energy transfer across the boundaries of the system.
b. combustion of fuels within the system.
c. radioactive decay of elements within the system.
d. all of the above.
e. only (b) and (c) above.
a
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Each pattern shown below would appear on a screen when monochromatic light first passes through a narrow slit of width a and then strikes a screen. The darkest areas on the page represent the brightest areas on the screen. In which case is the slit illuminated with light of the longest wavelength?
a.
b.
c.
A. +x direction B. -x direction C. +y direction D. -y direction E. +z direction F. -z direction T. The field is zero.
The rate of heat flow per unit length q/L through a hollow cylinder of inside radius ri and outside radius ro is q/L = ( A k ?T)/(ro – ri) where A = 2? (ro – ri)/ln(ro/ri). Determine the per cent error in the rate of heat flow if the arithmetic mean area ? (ro + ri) is used instead of the logarithmic mean area A for ratios of outside to inside diameters (Do/Di) of 1.5, 2.0, and 3.0. Plot the results.
GIVEN
• A hollow cylinder
• Inside radius = ri
• Outside radius = ro
• Heat flow per unit length as given above
FIND
(a) Per cent error in the rate of heat flow if the arithmetic rather than the logarithmic mean area is used for ratios of outside to inside diameters of 1.5, 2.0, and 3.0. (b) Plot the results
ASSUMPTIONS
• Radial conduction only
• Constant thermal conductivity
• Steady state prevails
SKETCH
The more massive planets in the solar system tend to be less dense than the lower mass planets
Indicate whether the statement is true or false