The graph between two quantities $P$ and $Q$ is a straight line passing through the origin when:

The related effort to derive the properties of a bigger, more complex system from the properties and interactions of its constituent simpler parts is:

Which of the following represents the fundamental forces of nature?

The diameter of a wire measured by a screw gauge of least count $0.001 \text{ cm}$ is $0.08 \text{ cm}$. The length measured by a scale of least count $0.1 \text{ cm}$ is $150 \text{ cm}$. When a weight of $100 \text{ N}$ is applied to the wire, the extension in length is $0.5 \text{ cm}$, measured by a micrometer of least count $0.001 \text{ cm}$. The error in the measured Young's modulus is $\alpha \times 10^9 \text{ N/m}^2$. The value of $\alpha$ is . . . . . . . (Ignore the contribution of the load to Young's modulus error calculation)

The phenomenon of physics that deals with the constitution and structure of matter at the minute scales of atoms and nuclei is

The physical quantities that have the same dimensions are: