Discuss the Miller-Urey experiment. What did these scientists had set out to prove?
What will be an ideal response?
An important experiment performed by Stanley Miller and Harold Urey in 1952 sought to re-create the presumed conditions in which life on Earth began. The Miller-Urey experiment consisted of a sterile, sealed glass container holding water, hydrogen, ammonia, and methane thought to resemble the young Earth's atmosphere. An electric arc inside the apparatus made sparks to simulate the effects of lightning. Miller and Urey let the experiment run for a week and then analyzed the material inside. They found that the interaction between the electric arc and the simulated atmosphere had produced many organic molecules from the raw material of the experiment, including such important building blocks of life as amino acids. When the experiment was run again using different energy sources such as hot silica to represent molten lava spilling into the ocean, similar molecules were produced. Even a source of ultraviolet radiation representing the amount of UV in sunlight was sufficient to produce complex organic molecules.
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A bullet is fired from ground level with a speed of 150 m/s at an angle 30.0° above the horizontal at a location where g = 10.0 m/s2. What is the horizontal component of its velocity after 4 seconds?
A) 150 m/s B) 35 m/s C) 130 m/s D) 75.0 m/s E) 37.5 m/s
In the context of the unified model of active galactic nuclei (AGN), you see jets of gas and radiation emerging perpendicular to the accretion disk of an AGN and coming straight at you if:
A) the accretion disk is tilted at an angle of 30 degrees to your line of sight. B) you look directly into the central cavity around the black hole. C) you view the accretion disk from its edge. D) the accretion disk is tilted at an angle of 60 degrees to your line of sight.
Which one of the arrows below most closely indicates the direction of the bob’s acceleration when it is at point 2?
A. A
B. B
C. C
D. D
E. E
F. F
Two objects of the same size, but unequal weights are dropped from a tall tower. Taking air resistance into consideration, the object to hit the ground first will be the
A) lighter object. B) heavier object. C) Both hit at the same time. D) not enough information