Which of the following is not considered a likely solution to the question of why we are not currently aware of a galactic civilization?
A) There is no galactic civilization because civilizations are not common.
B) There is no galactic civilization because civilizations do not leave their home worlds.
C) The galactic civilization is deliberately avoiding contact with us.
D) The galactic civilization probably is undetectable to us because it makes use of technologies that do not obey the known laws of physics.
E) There is no galactic civilization because most civilizations destroy themselves before achieving interstellar travel.
D
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A cylindrical tank is assembled by welding steel sections circumferentially. Tank diameter is 1.5 m, thickness is 20 mm, and internal pressure is 2.0 MPa. The maximum shear stress in the cylindrical part of the tank is approximately:
(A) 17 MPa
(B) 26 MPa
(C) 34 MPa
(D) 38 MPa
The advantage of a convex mirror is that it has a __________ field of view
a. narrow b. linear c. wide d. open
The planet Venus requires 225 days to orbit the Sun, which has a mass M = 1.99 × 1030 kg, in an almost circular trajectory. Calculate the radius of the orbit and the orbital speed of Venus as it circles the Sun.
What will be an ideal response?
A 9.0-V battery costs $1.49 and will run a portable CD player for 6.0 hours before running down and needing to be replaced
If this battery supplies a current of 25 mA to the player, what is the cost of the energy provided by the battery in dollars per kWh? A) $11/kWh B) $11,000/kWh C) $1100/kWh D) $110/kWh