Two planets each travel in a circular orbit about a star at radii of 
= 2R and 
= R, respectively. What is the ratio of their periods 
A. 1.6
B. 2.8
C. 1.3
D. 1.4
E. 2.0
B. 2.8
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Lens-Maker Formula: A thin double-convex lens is intended to focus the image of an object onto a screen so that the image is life-sized on the screen. The lens has equal-magnitude radii of 83 cm and a refractive index of 1.6. (a) What is the distance d from the image to the screen?(b) What is the total distance L between the object and the image?
A. (a) d = 138 cm (b) L = 276 cm B. (a) d = 276 cm (b) L = 552 cm C. (a) d = 69 cm (b) L = 35 cm D. (a) d = -138 cm (b) L = -276 cm
Compute the average emittance of anodized aluminum at 100°C and 650°C from the spectral curve. Assume ?? = 0.8 for ? > 9 ?m
GIVEN
The spectral curve for anodized aluminum
FIND
The average emittance (?) at (a) 100°C = 373 K, and, (b) 650°C = 923 K
SKETCH
PROPERTIES AND CONSTANTS
the Stephan-Boltzmann constant (?) = 5.67 10–8 W/(m2 K4)
A 2.0-cm length of wire centered on the origin carries a 20-A current directed in the positive y direction. Determine the magnetic field at the point x = 5.0 m on the x-axis
a. 1.6 nT in the negative z direction b. 1.6 nT in the positive z direction c. 2.4 nT in the negative z direction d. 2.4 nT in the negative z direction e. None of the above
For germanium at a tensile stress of 41 MPa and a temperature of 695°C, what is the primary creep mechanism? The shear modulus of germanium is 41 GPa.
What will be an ideal response?