Suppose you see two main-sequence stars of the same spectral type. Star 1 is dimmer in apparent brightness than Star 2 by a factor of 100. What can you conclude? (Neglect any effects that might be caused by interstellar dust and gas.)
A) Without first knowing the distances to these stars, you cannot draw any conclusions about how their true luminosities compare to each other.
B) The luminosity of Star 1 is a factor of 100 less than the luminosity of Star 2.
C) Star 1 is 100 times more distant than Star 2.
D) Star 1 is 100 times nearer than Star 2.
E) Star 1 is 10 times more distant than Star 2.
E
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Thin Lenses: A 4.0-cm-tall object is placed 50.0 cm from a diverging lens having a focal length of magnitude 25.0 cm. What is the nature and location of the image?
A. A real image, 4.0 cm tall, 20 cm other side of the object B. A virtual image, 4.0 cm tall, 20 cm other side of the object C. A virtual image, 2.0 cm tall, 10 cm other side of the object D. A virtual image, 1.3 cm tall, 16.7 cm same side as the object E. A real image, 1.3 cm tall, 16.7 cm same side as the object
A CD with a diameter of 12.0 cm starts from rest and with a constant angular acceleration of 1.0 rad/sec2 acquires an angular velocity of 5.0 rad/sec. The CD continues rotating at 5.0 rad/sec for 15.0 seconds and then slows to a stop in 12.0 second with a constant angular deceleration. What is the tangential velocity of a point 4.0 cm from the center at the time 2.0 seconds from the start?
A. 0.060 m/s B. 0.080 m/s C. 0.10 m/s D. 0.14 m/s E. 0.18 m/s
While the gondola is rising at a speed of 5.0 m/s, a passenger in a balloon-supported gondola throws a small ball up at a speed of 2.0 m/s relative to his body. A person who measures the ball's velocity at the instant of release will find that the ball's velocity relative to the ground at that instant is
a. 2.0 m/s, up. b. 2.8 m/s, down. c. 3.0 m/s, up. d. 5.0 m/s, up. e. 7.0 m/s, up.
Who first accurately measured the value for the charge of the electron?