The asker of the second question needs a tutorial in radiometric dating. There is little likelihood that the daughter isotope has the same atomic weight as the parent isotope. To measure the mass isotopes doesn't tell us how many atoms of each exist. To get around that let's pretend — which will likely serve the purpose ineptly intended — that the values give an the particle ratio, 125:875.
<span>The original parent isotope count was 125 + 875 = 1000. The remaining parent isotope is 125/1000 or 1/8. 1/8 = (1/2)^h, where h is the number of half-lives. </span>
<span>h = log (1/8) ÷ log(1/2) = 3 </span>
<span>And 3 half-lives • 150,000 years/half-life = 450,000 years.</span>
Answer:
, 
Explanation:
The situation can be modelled by applying the Principle of Angular Momentum Conservation:

The final angular speed is:



The tangential velocities of the wheel and the clay are, respectively:




Sound waves travel faster through <em>solids</em> than they do through gases or liquids. <em>(C) </em>They don't travel through vacuum at all.
Example:
Speed of sound in normal air . . . around 340 m/s
Speed of sound in water . . . around 1,480 m/s
Speed of sound in iron . . . around 5,120 m/s