A boy throws a ball to another boy who throws it back with half the original speed. What is the ratio of the final kinetic energy to the initial kinetic energy of the ball?
A) 0.25
B) 0.50
C) 2.00
D) 0.75
E) 1.0
A
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This figure shows frames from a computer simulation of star formation, starting at the left with a large molecular cloud measuring more than a light-year across. What is happening as time passes (from left to right)?
A) The cloud is fragmenting into smaller pieces that will form stars. B) The cloud is developing hot spots that shine more brightly within it. C) Magnetic fields are forcing the gas to align in intricate ways along twisted magnetic field lines. D) The cloud has been hit by a shock wave from a nearby stellar explosion, which causes the gas to move violently around.
How is the sunspot cycle directly relevant to us here on Earth?
A) The sunspot cycle strongly influences Earth's weather. B) The Sun's magnetic field, which plays a major role in the sunspot cycle, affects compass needles that we use on Earth. C) The brightening and darkening of the Sun that occurs during the sunspot cycle affects plant photosynthesis here on Earth. D) Coronal mass ejections and other activity associated with the sunspot cycle can disrupt radio communications and knock out sensitive electronic equipment. E) The sunspot cycle is the cause of global warming.
The Garfield Thomas water tunnel at Pennsylvania State University has a circular cross-section that constricts from a diameter of 3.6 m to the test section, which is 1.2 m in diameter. If the speed of flow is 2.0 m/s in the large-diameter pipe, determine the speed of flow in the test section
a. 9.0 m/s c. 27 m/s b. 18 m/s d. 1.0 m/s
A star with an apparent magnitude of +2.3 and an absolute magnitude of +5.9 lies ________ than 10 parsecs away
Fill in the blank(s) with correct word