A piece of ice is floating in a glass of water. When ice melts, water level MCQ with Answer and Explanation

Explanation:
The area under velocity-time graph gives displacement when direction is considered (signed area), and distance travelled when absolute values are taken (unsigned area). For unidirectional motion, both are equal. Velocity is rate of change of displacement, so integrating velocity over time yields displacement. This graphical interpretation is fundamental in kinematics. Memory tip: Slope of v-t graph = acceleration; area under v-t graph = displacement. Competitive exams often combine graph analysis with conceptual understanding to test depth of knowledge in motion topics.

Explanation:
Hydrogen fusion to helium releases energy.

Explanation:
Polarization requires transverse waves (oscillations perpendicular to propagation). Light, radio waves, X-rays are electromagnetic transverse waves and can be polarized. Sound waves in air are longitudinal (oscillations parallel to propagation) and cannot be polarized. Memory tip: 'Polarization ⇒ transverse waves only; sound is longitudinal ⇒ no polarization'. This wave property question tests understanding of wave types, frequently examined in competitive exams. Always classify waves as transverse/longitudinal to determine polarization possibility; this is a common conceptual trap.