Distinguish an Sa from an Sc galaxy
What will be an ideal response?
Sa spirals have more tightly wound spiral arms, and a wider nuclear bulge; Sc are flatter, dustier, and have looser arms.
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An intrinsically very bright star might appear faint if it is far away
Indicate whether the statement is true or false
What is the kinetic energy of a 200-kg satellite as it follows a circular orbit of radius 8.0 × 10^6 m around the Earth? (Mass of Earth = 6.0 × 10^24 kg.)
a. 5.0 × 10^9 J b. 1.0 × 10^10 J c. 1.5 × 10^10 J d. 2.0 × 10^10 J e. 2.5 × 10^9 J
A simply supported steel beam of length L 5 1.5 m and rectangular cross section (h 5 75 mm, b 5 20 mm) carries a uniform load of q 5 48 kN/m that includes its own weight. The maximum transverse shear stress on the cross section at 0.25 m from the left support is approximately:
(A) 20 MPa
(B) 24 MPa
(C) 30 MPa
(D) 36 MPa
A large gravel truck is loosely covered with a tarpaulin. The edges of the tarp are tied down to the truck. When the truck is at rest the tarp is flat. When it cruises at highway speeds
A. fly up off the table. B. not move at all, if you are careful to blow underneath it. C. flatten down on the table.