The best way to find the exact distance to the Moon is to:
A) measure its exact size in the telescope.
B) use radar reflection times, about 2.56 second.
C) bounce lasers off the retroreflectors left on the surface by the Apollo landings.
D) make parallax measurements from observatories on opposite sides of the Earth.
E) use stellar occultations for precise timings of the Moon's position.
C
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A 0.28-kg stone you throw rises 34.3 m in the air. The impulse the stone receives from your hand while being thrown is
A.
s, up.B.
s, down.C.
s, up.D.
s, down.E.
s, up.You want to produce a casting of sterling silver that is silver plus 13 atomic % copper. Pure silver is too soft for many applications, and adding 13 atomic % copper strengthens the silver without significantly changing the color. To produce the sterling silver casting, you are going to melt commercially pure silver and copper in a furnace, and then you will pour the liquid metal mixture into a mold. The following questions relate to this alloy.
(a) In selecting a furnace, what must be the minimum value of the high-temperature capability of your selected furnace?
(b) In transferring the liquid metal from the furnace to the mold, what is the minimum temperature that the metal can reach so that none of the metal has solidified?
(c) After the casting has cooled to room temperature, what phases are present, what is the equilibrium chemical composition (Ci) of each phase present, and what is the atom fraction (fi) of each phase present?
Which of the following is a neutral subatomic particle?
a. neutron b. proton c. electron d. neutron and proton e. electron and neutron
Which of the following best describes the size and distance relationship of our Sun and the nearest star?
A) A tennis ball here, another on the Moon B) Two beach balls separated by 100 city blocks C) Two grains of sand separated by 100 light-years D) Two golf balls separated by 300 kilometers E) Two baseballs separated by 100 yards