A rock sample contains 1/4 micrograms of the parent radioactive isotope K-40 and 3/4 micrograms of its daughter isotope Ar-40. If the half-life of this decay is 1.25 billion years, how old is this rock?
A) 5.00 billion years
B) 3.75 billion years
C) 1.25 billion years
D) 2.50 billion years
D
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Simple Pendulum: Grandfather clocks are designed so they can be adjusted by moving the weight at the bottom of the pendulum up or down. Suppose you have a grandfather clock at home that runs fast. Which of the following adjustments of the weight would make it more accurate? (There could be more than one correct choice.)
A. Raise the weight. B. Lower the weight. C. Add more mass to the weight. D. Remove some mass from the weight. E. Decrease the amplitude of swing by a small amount.
A skater can spin faster by pulling her arms closer to her body or spin slower by spreading her arms out from her body. This is due to
A) the law of gravity. B) Newton's third law. C) conservation of momentum. D) conservation of angular momentum. E) conservation of energy.
The type of radiation affected by greenhouse gasses is
a. UV radiation. b. IR radiation. c. visible radiation. d. gamma radiation.
Polaris is always the polestar.
Answer the following statement true (T) or false (F)