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marusya05 [52]
3 years ago
9

After a plant or animal dies the 14C content decreases with a half-life of 5730 years. If an archaeologist finds an ancient fire

pit containing partially consumed firewood, and the 14C content of the wood is only 15.5% that of an equal carbon sample from a present-day tree, what is the age (in years) of the ancient site?
Physics
1 answer:
Shalnov [3]3 years ago
6 0

Answer:

age of the site is 15411.75 years old

Explanation:

Given data

plant or animal dies = 14C

time period = 5730 year

carbon = 15.5%

to find out

age (in years) of the ancient site

solution

we know that Final value = Initial value  × 0.5^{n}

here n is half life passed

so for 15.5%

15.5% = 100% of  0.5^{n}

0.155 = 1 × 0.5^{n}

now take log both side

log 0.155 = log  0.5^{n}

n = log 0.155 / log 0.5

n = 2.68966

we know here  5730 years in half life

so for 2.68966 half-lives = 2.68966 × 5730  =  15411.7518

age of the site is 15411.75 years old

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Answer:

An atmosphere is the layers of gases surrounding a planet or other celestial body. Earth's atmosphere is composed of about 78% nitrogen, 21% oxygen, and one percent other gases

7 0
2 years ago
A boy jumps from rest, straight down from the top of a cliff. He falls halfway down to the water below in 0.866 s. How much time
Iteru [2.4K]
<h2>Entire trip takes 1.22 seconds.</h2>

Explanation:

We have equation of motion s = ut + 0.5 at²

        Initial velocity, u = 0 m/s

        Acceleration, a = 9.81 m/s²  

        Time, t = 0.866 s      

     Substituting

                      s = ut + 0.5 at²

                      s = 0 x 0.866 + 0.5 x 9.81 x 0.866²

                      s = 3.68 m

      Halfway is 3.68 m

Total height = 2 x 3.68 = 7.36 m

We have equation of motion s = ut + 0.5 at²

        Initial velocity, u = 0 m/s

        Acceleration, a = 9.81 m/s²  

        Time, t = ?

        Displacement, s  = 7.36 m

     Substituting

                      s = ut + 0.5 at²

                      7.36 = 0 x t + 0.5 x 9.81 x t²

                      t = 1.22 s

Entire trip takes 1.22 seconds.

7 0
3 years ago
A truck is hauling a 300-kg log out of a ditch using a winch attached to the back of the truck. Knowing the winch applies a cons
torisob [31]

Answer:

0.1 s

Explanation:

The net force on the log is F - f = ma where F = force due to winch = 2850 N, f = kinetic frictional force = μmg where μ = coefficient of kinetic friction between log and ground = 0.45, m = mass of log = 300 kg and g = acceleration due to gravity = 9.8 m/s² and a = acceleration of log

So F - f = ma

F - μmg = ma

F/m - μg = a

So, substituting the values of the variables into the equation, we have

a = F/m - μg

a = 2850 N/300 kg - 0.45 × 9.8 m/s²

a = 9.5 m/s² - 4.41 m/s²

a = 5.09 m/s²

Since acceleration, a = (v - u)/t where u = initial velocity of log = 0 m/s (since it was a rest before being pulled out of the ditch), v = final velocity of log = 0.5 m/s and t = time taken for the log to reach a speed of 0.5 m/s.

So, making t subject of the formula, we have

t = (v - u)/a

substituting the values of the variables into the equation, we have

t = (v - u)/a

t = (0.5 m/s - 0 m/s)/5.09 m/s²

t = 0.5 m/s ÷ 5.09 m/s²

t = 0.098 s

t ≅ 0.1 s

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Answer:

a and b are the correct answers

Explanation:

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