Answer is A, the mass and radius of the planet.
The law of universal gravitation states that gravitational force (weight) is equal to G(m1+m2)/r, and G is a constant number. m is mass and r is radius, so the answer is A.
Equation for Half life :
A = a(0.5)^(t/h)
A is current amount, "a" is initial amount, h is halflife, t is time
5 = 40(0.5)^(t/1.3x10^9)
5/40 = (0.5)^(t/1.3x10^9)
take the log of both sides , power rule
Log(5/40) = (t/1.3x10^9) * Log(0.5)
(1.3x10^9) * Log(5/40) / Log(0.5) = t
3.9x10^9 years = t
And if you think about what a half life is, the time it take for the amount to reduce to half.
40/2 = 20
20/2 = 10
10/2 = 5
It went through 3 half-lifes
3 * 1.3x10^9 = 3.9x10^9 years
Answer:
I think the answer is: one element and one compound
Explanation:
I'm really sorry if it's wrong.
Rocks are heated, metamorphosed, melted,
weathered, sediment is transported, deposited and lithified, then it may be metamorphosed
again in yet another cycle. This recycling of the material of the Earth's crust has
been going on for billions of years, as far back as there is a preserved geologic record
(about 4 billion years). Weathering and erosion at the Earth's surface can break
down rocks into small bits. These can be
deposited as sediments that become sedimentary
rocks. Burial, with rising pressure and temperature, can alter sedimentary (as well as any
other) rocks to form metamorphic rocks.
Continued rise in temperature can eventually melt
rocks and produce magma. Cooling of magmas leads to igneous rocks, etc.