Chapter 43, Problem 1P

(a)

To determine

The order of magnitude of number of protons in human body.

Answer to Problem 1P

The order of protons in human body is ${10}^{28}$.

Explanation of Solution

A human body is mostly composed of water. In water molecule there are $8$ protons and $10$ neutrons. Thus the order of proton and neutron in a human body is almost same.

Consider an average human body composed of $35\text{kg}$ proton and $35\text{kg}$ neutrons.

Write the number of nucleon.

    $n=\frac{m_n}{M}$

Here, $n$ is the number of nucleons, $m_n$ is the average mass of a nucleon, $M$ is mass.

Conclusion:

Substitute $35\text{kg}$ for $M$, $1.67\times {10}^{-27}\text{kg}$ for $m_n$ to determine the number of the nucleons.

    $\begin{array}{c}n=\frac{35\text{ kg}}{1.67\times {10}^{-27}\text{ kg}}\\ \approx {10}^{28}\end{array}$

The order of protons in human body is ${10}^{28}$.

(b)

To determine

The order of magnitude of number of neutrons in human body.

Answer to Problem 1P

The order of neutron in human body is ${10}^{28}$.

Explanation of Solution

A human body is mostly composed of water. In water molecule there are $8$ protons and $10$ neutrons. Thus the order of proton and neutron in a human body is almost same.

Thus the order of neutron in human body is ${10}^{28}$.

Conclusion:

The order of neutron in human body is ${10}^{28}$.

(c)

To determine

The order of magnitude of number of electrons in human body.

Answer to Problem 1P

The order of electrons in human body is ${10}^{28}$.

Explanation of Solution

A human body is mostly composed of water. In water molecule the number of protons and electrons are exactly same. Thus the order of number of electrons will be same as the order of proton in human body.

The order of electrons in human body is ${10}^{28}$.

Conclusion:

The order of electrons in human body is ${10}^{28}$.