The Drake equation allows us to estimate the number of
A) intelligent civilizations that have existed in our galaxy during its entire lifetime
B) habitable planets on which life has arisen
C) intelligent civilizations capable of traveling to the Earth
D) intelligent civilizations capable of communicating in our galaxy now
D
You might also like to view...
Energy Conservation With Conservative Forces: A small but dense 2.0-kg stone is attached to one end of a very light rod that is 1.2 m long. The other end of the rod is attached to a frictionless pivot. The rod is raised until it is vertical, with the stone above the pivot. The rod is released and the stone moves in a vertical circle with no air resistance. What is the tension in the rod as the stone moves through the bottom of the circle?
A. 20 N B. 40 N C. 60 N D. 80 N E. 100 N
Conservation of Momentum: Two astronauts, of masses 60 kg and 80 kg, are initially right next to each other and at rest in outer space. They suddenly push each other apart. What is their separation after the heavier astronaut has moved 12 m?
A. 9.0 m B. 16 m C. 21 m D. 24 m E. 28 m
What are the mechanisms that restrict the mass range of stars to about 0.1 to 100 solar masses?
What will be an ideal response?
What is the limiting angle of resolution for a lens of radius 2.0 mm when viewing with light having a wavelength of 600 nm?
A) 1.8 × 10-7 rad B) 1.3 × 10-4 rad C) 1.5 × 10-7 rad D) 1.5 × 10-4 rad E) 1.8 × 10-4 rad