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slava [35]
2 years ago
13

The rubidium isotope 87Rb is a β emitter that has a half-life of 4.9 ✕ 1010 y that decays into 87Sr. It is used to determine the

age of rocks and fossils. Rocks containing the fossils of early animal have a ratio of 87Sr to 87Rb of 0.0040. Assuming that there was no 87Sr present when the rocks were formed, calculate the age of the fossils.
Physics
1 answer:
fredd [130]2 years ago
4 0

Answer:

t = 39.04 1010 year

Explanation:

This is a nuclear disintegration exercise that is governed by the equation.

     N = N0 e (-lam t)

The average life time is related to nuclear activity

      T ½ = ln 2 / lam

Let's use these two equations for exercise, let's start by finding nuclear activity

     Lam = ln 2 / T ½

     Lam = ln 2 / 4.9 10 10

    Lam = 0.14146 10-10 y-1

They tell us that the relationship atoms

      No / N = 0.0040

Let's look

       No / N = 1/0040

       N/No = 250                                                                                                                                                                                

Let's calculate the time

       (-lam t) = ln (N / No)

,        t = - 1 / lam ln (n / No)

        t = - 1 / 0.14146 10-10 ln (250)

        t = 39.04 1010 year

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Which phenomenon occurs when a wave encounters a non–transmitting barrier
SpyIntel [72]

Answer:

Absorption

Explanation:

A non-transmitting barrier would not allow a wave to go through. When a wave is unable to pass through a barrier, it is not transmitted and can get absorbed or reflected back. The wave can also try to go round the barrier.

Most likely, the wave gets absorbed by the barrier and it stops it.

6 0
3 years ago
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You perform a double‑slit experiment in order to measure the wavelength of the new laser that you received for your birthday. Yo
BigorU [14]

Answer:

\lambda = 6.25\times10^{-9}= 625 nm

Explanation:

We now that for

for maximum intensity(bright fringe) d sinθ=nλ n=0,1,2,....

d= distance between the slits, λ= wavelength of incident ray

for small θ, sinθ≈tanθ= y/D where y is the distance on screen and D is the distance b/w screen and slits.

Given

d=1.19 mm, y=4.97 cm,  and,   n=10,   D=9.47 m

applying formula

λ= (d*y)/(D*n)

putting values we get

\lambda = \frac{1.19\times10^{-3}\times4.97\times10^{-2}}{9.47\times10}

on solving we get

\lambda = 6.25\times10^{-9}= 625 nm

8 0
2 years ago
What's a good way to determine the net force of something
ollegr [7]
By adding up all the individual forces of the object
3 0
2 years ago
1. If 800 C of electric charge passed through a light bulb in 4 min; what is the mag
9966 [12]

The electric current passing through the bulb would be 3.3A

<u>Explanation:</u>

Given:

Electric charge, q = 800C

Time, t = 4 min

           = 4 X 60 sec

           = 240 sec

Electric current, I = ?

We know,

Current  = \frac{Charge}{Time}

On substituting the value we get:

I = \frac{800}{4 X 60} \\\\I = 3.3A

Thus, the electric current passing through the bulb would be 3.3A

5 0
2 years ago
What is the angle of the 2nd order bright fringe produced by two slits that are 8.25x10-5m apart if the wavelength of the incide
dexar [7]

In order to calculate the angle, we can use the formula below for a constructive interference (the interference is constructive because the fringe is bright):

d\sin\theta=m\lambda

Where d is the distance between the slits, m is the order of the interference and lambda is the wavelength.

So, using d = 8.25 * 10^-5, m = 2 and lambda = 4.5 * 10^-7, we have:

\begin{gathered} 8.25\cdot10^{-5}\cdot\sin\theta=2\cdot4.5\cdot10^{-7}\\ \\ \sin\theta=\frac{9\cdot10^{-7}}{8.25\cdot10^{-5}}\\ \\ \sin\theta=1.091\cdot10^{-2}\\ \\ \theta=0.625° \end{gathered}

Therefore the correct option is the second one.

5 0
1 year ago
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