The dark area stretching from the center of this picture to the upper right is about 50 light-years long and lies in the plane of the Milky Way Galaxy. What is it?
A) a star-forming cloud
B) a region of the galactic plane in which there are few stars
C) the expanding remains of a supernova
D) a black hole
A) a star-forming cloud
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The work done in moving a positive charge against an electric field does not depend on the path chosen in moving the charge in that field. Based on the statement, what kind of force field is the electrostatic field?
A) discrete B) quantized C) polarized D) conservative E) nonconservative
In a problem using energy considerations to solve for the speed of a ball thrown from the top of a building when it strikes the ground below, where should the potential energy have its zero value?
a. It should be at the level from where the ball is thrown. b. It should be at the ground level where the ball hits. c. It should be slightly below ground level so the potential energy is always positive. d. It doesn't matter since only differences in potential energy matter in solutions.
An area of 100 cm2 is how many square meters?
A) 1.00 B) 1.00 × 102 C) 1.00 × 10-2 D) 1.00 × 104 E) 1.00 × 10-3
A heat engine operating between 40°C and 380°C has an efficiency 60% of that of a Carnot engine operating between the same temperatures. If the engine absorbs heat at a rate of 60 kW, at what rate does it exhaust heat?
What will be an ideal response?