The diagram below illustrates the radioactive decay of Potassium (40K), which has a half-life of 1.3 billion years. If a lunar rock is found that currently contains 5 grams of 40K, and it is determined that the sample contained 20 grams when it was formed, how old is the lunar rock?
a.
6.5 billion years
b.
19.5 billion years
c.
2.6 billion years
d.
3.9 billion years
e.
4.6 billion years
C
You might also like to view...
The largest diameter telescopes are used to observe
A) radio waves. B) infrared light. C) visible light. D) ultraviolet light. E) x-rays.
In the absence of air resistance, a boulder and a pebble dropped from rest will fall with equal
1) forces of gravity. 2) accelerations. 3) energies. 4) all these. The reason that this quantity is not greater for the boulder than the pebble is that 5) both the boulder and the pebble fall at the same speed. 6) the initial potential energies of each is the same. 7) gravitational force acting on each is the same. 8) the greater gravitational force on the boulder acts on a correspondingly greater mass.
Spherical Mirrors: If you stand in front of a convex mirror, at the same distance from it as its focal length,
A. you won't see your image because there is none. B. you won't see your image because it is focused at infinity. C. you will see your image and you will appear smaller than you. D. you will see your image and you will appear larger than you. E. you will see your image and it will be the same size as you except upside down.
Which condition of motion must be met with regard to a charged particle if it is in the process of emitting electromagnetic radiation?
a. moves at constant velocity b. accelerates c. moves at the speed of light d. moves parallel to a uniform magnetic field