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inysia [295]
3 years ago
7

A paleontologist estimates that when a particular rock formed, it contained 12 mg of the radioactive isotope potassium-40, which

has a half-life of 1.26 billion years. The rock now contains 3 mg of the isotope. About how old is the rock? Enter in billions of years.
Physics
1 answer:
leva [86]3 years ago
7 0

Answer:

t = 2.52 billion \:years

Explanation:

As we know by radioactivity law

N = N_o e^{-\lambda t}

so here we will have

N = 3 mg

N_o = 12 mg

now we will have

3 = 12 e^{-\lambda t}

\lambda t = ln 4

now we also know that

\lambda = \frac{ln2}{1.26 \times 10^6 yrs}

t = 1.26\times 10^6\times \frac{ln4}{ln2}

t = 2.52 billion \:years

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Ben walks 500 meters from his house to the corner store. He then walks back toward his house but stops to talk to a
motikmotik

Answer: 0.3

Explanation:

6 0
3 years ago
The Steamboat Geyser in Yellowstone National Park shoots water into the air at 48.0 m/s. How
qwelly [4]

Answer:

The maximum height reached by the water is 117.55 m.

Explanation:

Given;

initial velocity of the water, u = 48 m/s

at maximum height the final velocity will be zero, v = 0

the water is going upwards, i.e in the negative direction of gravity, g = -9.8 m/s².

The maximum height reached by the water is calculated as follows;

v² = u² + 2gh

where;

h is the maximum height reached by the water

0 = u² + 2gh

0 = (48)² + ( 2 x -9.8 x h)

0 = 2304 - 19.6h

19.6h = 2304

h = 2304 / 19.6

h = 117.55 m

Therefore, the maximum height reached by the water is 117.55 m.

7 0
2 years ago
Read 2 more answers
A rough estimate of the radius of a nucleus is provided by the formula r 5 kA1/3, where k is approximately 1.3 × 10213 cm and A
Sphinxa [80]

Answer:

Density of 127 I = \rm 1.79\times 10^{14}\ g/cm^3.

Also, \rm Density\ of\ ^{127}I=3.63\times 10^{13}\times Density\ of\ the\ solid\ iodine.

Explanation:

Given, the radius of a nucleus is given as

\rm r=kA^{1/3}.

where,

  • \rm k = 1.3\times 10^{-13} cm.
  • A is the mass number of the nucleus.

The density of the nucleus is defined as the mass of the nucleus M per unit volume V.

\rm \rho = \dfrac{M}{V}=\dfrac{M}{\dfrac 43 \pi r^3}=\dfrac{M}{\dfrac 43 \pi (kA^{1/3})^3}=\dfrac{M}{\dfrac 43 \pi k^3A}.

For the nucleus 127 I,

Mass, M = \rm 2.1\times 10^{-22}\ g.

Mass number, A = 127.

Therefore, the density of the 127 I nucleus is given by

\rm \rho = \dfrac{2.1\times 10^{-22}\ g}{\dfrac 43 \times \pi \times (1.3\times 10^{-13})^3\times 127}=1.79\times 10^{14}\ g/cm^3.

On comparing with the density of the solid iodine,

\rm \dfrac{Density\ of\ ^{127}I}{Density\ of\ the\ solid\ iodine}=\dfrac{1.79\times 10^{14}\ g/cm^3}{4.93\ g/cm^3}=3.63\times 10^{13}.\\\\\Rightarrow Density\ of\ ^{127}I=3.63\times 10^{13}\times Density\ of\ the\ solid\ iodine.

7 0
3 years ago
What is the speed of the tip of the minute hand of a clock where the hand is of length 7cm?​
azamat

Explanation:

Q1) What is the speed of the tip of the minute hand of a clock where the hand is of length 7cm?

Ans1) speed, v=st=2πrT=2×227×7×10-260×60=119×10-4=1.22×10-4m/s

<h2><em><u>Hope it helps</u></em></h2>
5 0
3 years ago
Calculate the angle θ between the radius-vector of the point and the positive x axis (measured counterclockwise from the positiv
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The point obviously is in the 3rs quadrant

So

စ= tan^-1( y/x)-180

စ= -89.7°

6 0
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