Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Nuclei

Question:

Order of magnitude of density of uranium nucleus is $\left(m_p=1.67 \times 10^{-27} kg\right)$

Options:

$10^{20} kg / m^3$

$10^{17} kg / m^3$

$10^{14} kg / m^3$

$10^{11} kg / m^3$

Correct Answer:

$10^{17} kg / m^3$

Explanation:

The order of magnitude of mass and volume of uranium nucleus will be $m â‰ƒ A\left(1.67 × 10^{-27} kg\right)$

$V=\frac{4}{3} \pi r^3 \simeq \frac{4}{3} \pi\left[\left(1.25 \times 10^{-15} \mathrm{~m}\right) A^{1 / 3}\right]^3 \simeq\left(8.2 \times 10^{-45} \mathrm{~m}^3\right) \mathrm{A}$

Hence, $\rho=\frac{m}{V}=\frac{A\left(1.67 \times 10^{-27} \mathrm{~kg}\right)}{\left(8.2 \times 10^{-45} \mathrm{~m}^3\right) \mathrm{A}} \simeq 2.0 \times 10^{17} \mathrm{~kg} / \mathrm{m}^3$.