Which of the following statements is true of white dwarfs?
A) Some of them are among the hottest stars known.
B) Few of them are positioned in the upper-right corner of the Hertzsprung-Russell (H-R) diagram.
C) They have high luminosities.
D) They have a very big surface area from which they radiate energy.
A
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Massive-star supernovae and white-dwarf supernovae work equally well as standard candles for measuring cosmic distances
Indicate whether the statement is true or false
An object moves in a direction parallel to its length with a velocity that approaches the velocity of light. The mass of this object as measured by a stationary observer
A) approaches infinity. B) approaches zero. C) increases slightly. D) does not change.
A body on the surface of the Earth weighs 400 lb. The radius of the Earth is about 4,000 miles. If this same body were placed on a 4,000-mile-high tower, its weight would be __________
Fill in the blank(s) with correct word
A child throws a ball with an initial speed of 8.0 m/s at an angle of 40° above the horizontal. The ball leaves her hand 1.0 m above the ground and experiences no appreciable air resistance as it moves
(a) How far from where the child is standing does the ball hit the ground? (b) How long is the ball in flight before it hits the ground? (c) What is the magnitude of the ball's velocity just before it hits the ground?