Physics: The half-life of nickel-63 is 100 years. If a sample of nickel-63 decays until 6.25% of the original sample remains, how much time has passed? * 6.25 years 100 years 400 years 1600 years

The half-life of nickel-63 is 100 years. If a

myhomeacc32

24.01.2022

400 years

Explanation:

The equation that describes the decay of a radioactive sample is:

$m(t)=m_0 (\frac{1}{2})^{t/t_{1/2}}$ (1)

where

m(t) is the amount of sample left at time t

m_0 is the initial amount of the sample

$t_{1/2}$ is the half-life, which is the time taken for the sample to halve

In this problem we have:

$t_{1/2}=100 y$ is the half-life of Nickel-63

After a time t, the amount of sample left is 6.25% of the original one, which means that

$\frac{m(t)}{m_0}=\frac{6.25}{100}$

So we can rewrite the equation (1) and solving for t to find the time:

$\frac{6.25}{100}=(\frac{1}{2})^{t/t_{1/2}}\\\rightarrow \frac{t}{t_{1/2}}=4\\t=4t_{1/2}=4(100)=400 y$

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robert7248

16.10.2021

1.75 / 2 = 0.875 m

Explanation:

Provided the mirror is vertical and you are standing upright.

It could be most any altitude if the mirror is allowed any orientation.

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