Ask question

Ask question

All categories

musickatia [10]

3 years ago

8

We have a radioactive isotope called RI which has a half-life of 12 million years. A geologist has used radiometric dating and d

etermined the rock to be approximately 36 million years old. How many half lives have taken place?

2 answers:

dedylja [7]3 years ago

5 0

Answer:

3

Explanation:

half life, T = 12 million years

total life, t = 36 million years

Let n be the number of half lives.

n = Total life / half life

n = 36 / 12 = 3

So, the number of half lives are 3.

Irina-Kira [14]3 years ago

5 0

Answer:

Explanation:

Given that,

Half-life is 12million year's

t½ = 12million years

If the element is approximately 36millions years old.

We to know how many half lives have taken place.

The first half life is

12 million years

The second half life is

2 ×12 = 24 millions years

The third half life is

3×12 = 36 million years

Since the element is 36 millions years old, so 3 half life have take place.

You might be interested in

Mark creates a graphic organizer to review his notes about electrical force. Which labels belong in the regions marked X and Y?

sveta [45]

Answer:

The correct answer is A

Explanation:

The question requires as well the attached image, so please see that below.

Coulomb's Law.

The electrical force can be understood by remembering Coulomb's Law, that describes the electrostatic force between two charged particles. If the particles have charges $q_1$ and $q_2$ , are separated by a distance r and are at rest relative to each other, then its electrostatic force magnitude on particle 1 due particle 2 is given by:

$|F|=k \cfrac{q_1 q_2}{r^2}$

Thus if we decrease the distance by half we have

$r_1 =\cfrac r2$

So we get

$|F|=k \cfrac{q_1 q_2}{r_1^2}$

Replacing we get

$|F|=k \cfrac{q_1 q_2}{(r/2)^2}\\|F|=k \cfrac{q_1 q_2}{r^2/4}$

We can then multiply both numerator and denominator by 4 to get

$|F|=k \cfrac{4q_1 q_2}{r^2}$

So we have

$|F|=4 \left(k \cfrac{q_1 q_2}{r^2}\right)$

Thus if we decrease the distance by half we get four times the force.

Then we can replace the second condition

$q_{2new} =2q_2$

So we get

$|F|=k \cfrac{q_1 q_{2new}}{r_1^2}$

which give us

$|F|=k \cfrac{q_1 2q_2}{r_1^2}\\|F|=2\left(k \cfrac{q_1 q_2}{r_1^2}\right)$

Thus doubling one of the charges doubles the force.

So the answer is A.

8 0

3 years ago

Read 2 more answers

What potential difference is required in an electron microscope to give an electron wavelength of 4. 5 nm?

Lorico [155]

Potential difference required in an electron microscope to give an electron wavelength of 4. 5 nm will be 0.063 V.

The difference in potential between two points that represents the work involved or the energy released in the transfer of a unit quantity of electricity from one point to the other is called potential difference.

The wavelength of an electron is calculated for a given energy (accelerating voltage) by using the de Broglie relation between the momentum p and the wavelength λ of an electron

lambda = 4.5 nm = 4.5 * $10^{-9}$ m

h = $6.626 * 10^{-34}$ J s

e = 1.6 * $10^{-19}$ C

m = 9.1 * $10^{-31}$ kg

Energy = eV

lambda = h / $\sqrt{2mE}$ = h / $\sqrt{2m(eV)}$

$(lambda)^{2}$ = $h^{2}$ / (2m (eV))

V = $h^{2}$ / (2 m e $(lambda)^{2}$ )

V = $(6.626 * 10^{-34} )^{2}$ / 2 * 9.1 * $10^{-31}$ * 1.6 * $10^{-19}$ * $(4.9 * 10^{-9}) ^{2}$

V = 0.063 V

To learn more about wavelength of an electron here

brainly.com/question/17295250

#SPJ4

7 0

2 years ago

A car speedometer that is supposed to read the linear speed of the car uses a device that actually measures the angular speed of

nikklg [1K]

When a car<span> rounds a corner at a constant </span>speed<span>, its acceleration is zero. Suppose you are in a </span>car<span> that is going around a curve. The speedometer reads a constant 30 miles per hour. ... </span>Describe the speed<span> of the object from 4-6 seconds using the distance vs. time graph.</span>

4 0

3 years ago

An object floats in water with 5 8 of its volume submerged. The ratio of the density of the object to that of water is

ki77a [65]

Answer:

$\dfrac{5}{8}$

Explanation:

m = Mass of object = $\rho v$

m' = Mass of water = $\rho' v'$

$\rho$ = Density of object

$\rho'$ = Density of water

Weight of the water displaced is the force in the case of floating objects

According to the question

$v'=\dfrac{5}{8}v$

In the case of floating objects

$W=W'\\\Rightarrow mg=m'g\\\Rightarrow \rho vg=\rho'v'g\\\Rightarrow \rho v=\rho' \dfrac{5}{8}vg\\\Rightarrow \rho=\rho' \dfrac{5}{8}\\\Rightarrow \dfrac{\rho}{\rho'}=\dfrac{5}{8}$

The ratio of the density of the object to that of water is $\dfrac{5}{8}$

3 0

3 years ago

Why do animals float when they die

Gnom [1K]

Answer:

they don't float when they die unless they are in water

6 0

3 years ago