Suppose you find a rock and measure that 12.5% of the original uranium-235 still remains it, while the other 87.5% has decayed into lead-207. About how old is the rock?
a. 4.5 billion years
b. 1.25 billion years
c. 2.8 billion years
d. 2.1 billion years
Answer: d. 2.1 billion years
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Two wires, one copper and the other steel, of equal length stretch the same amount under an applied load P. The moduli of elasticity for each is Es 5 210 GPa and Ec 5 120 GPa. The ratio of the diameter of the copper wire to that of the steel wire is approximately:
(A) 1.00
(B) 1.08
(C) 1.19
(D) 1.32
You are studying a mystery companion to an evolved star, with mass transfer happening. Which of the following properties suggests that the companion is definitely a black hole?
A) The mystery companion has a mass of over 1.4 solar masses. B) The mystery companion has a mass of over 3 solar masses. C) The mystery companion has an X-ray emitting accretion disk. D) The mystery companion gives off periodic X-ray bursts.
Which alcohol is used as an antifreeze?
a. 2-Hydroxypropane b. Ethylene glycol c. Ethanol d. Methanol
The oblateness of the jovian planets' disks is caused by their ________
Fill in the blank(s) with correct word