Physics Concepts and Principles Quiz

A car is retarding when its velocity is decreasing. This can happen by slowing down in the current direction OR by speeding in the opposite direction (since velocity includes direction). Therefore, both scenarios are valid examples of retardation.

All objects with temperature above absolute zero emit electromagnetic radiation (thermal radiation). Lamp B (glowing) emits visible light plus thermal radiation. Lamp A (broken but still at room temperature) still emits thermal radiation in the infrared spectrum. Therefore, both lamps emit electromagnetic radiation.

Water seeks its own level due to water pressure increasing with depth (P = rho * g * h). In connected vessels, water flows until pressures at the same horizontal level equalize, which occurs when water surfaces are at the same height. Atmospheric pressure is the same on all surfaces and cancels out, while density and 'g' don't determine level-seeking behavior.

When the glass is whirled in a circular path, the flame points toward the center due to inertia. The more massive gases in the flame have greater inertia and resist the circular motion more than the lighter glass and air, causing them to lag inward relative to the center of rotation.

In free fall, all objects accelerate downward at g, eliminating the effective gravity that causes buoyancy. The helium balloon doesn't rise relative to you because there's no 'up' direction; everything falls together.

When iron is in the boat, it displaces water equal to its weight. When submerged, it displaces water equal to its volume. Since iron is denser than water, its volume is less than the volume of water with the same weight, so less water is displaced overall.

The fraction of an ice cube submerged depends only on the density ratio of ice to liquid, not on gravitational acceleration. This ratio is unchanged on the moon, so the submerged volume remains 9/10.

The metal fuselage of an airplane acts as a Faraday cage. If lightning strikes, the current flows through the metal skin and around the passenger cabin, protecting the occupants inside.

Water molecules are polar and align themselves in an electric field. Whether the rod is positive or negative, the polarization causes water to be attracted: positive and negative rods both induce the same attractive effect.

In a series circuit, current is the same through both bulbs. The bulb with higher resistance (the 40W bulb has higher resistance than 100W) dissipates more power (P=I²R), so it glows brighter.

To average 40 km/hr over 40 km, you must complete the trip in exactly 1 hour. But you already spent 30 minutes on the first 20 km (20/40 hr) plus 30 minutes on the next 10 km (10/20 hr), totaling 60 minutes. You have zero time left to cover the remaining 10 km, which is impossible.

According to Newton's law of cooling, heat loss rate is proportional to temperature difference. Adding cream sooner reduces the coffee's temperature earlier, creating a smaller temperature difference with surroundings and slower heat loss thereafter, resulting in hotter coffee at drinking time.

When feet are wet, the water evaporates upon contact with the heat, creating a brief protective layer of steam (Leidenfrost effect) and absorbing some heat energy, which results in feeling less heat initially compared to dry skin.

'Twice as hot' means doubling the absolute temperature. 10°C = 283K. Doubling gives 566K, which is 566 - 273 = 293°C. Note: option C has a typo (degree symbol should be °, not superscript °, but the value 293°C is correct).