Tag: science & technology

Density is mass divided by volume. When the volume is reduced to half while the mass remains constant, the density must double. The initial density of 1 kg/m³ becomes 2 kg/m³ after compression.

Newton's first law of motion, also known as the law of inertia, states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force. This describes the natural tendency of objects to resist changes in their motion.

The sensible heat equation is Q = C × ΔT, where Q is the heat gained or lost, C is the heat capacity, and ΔT is the temperature change. Heat capacity alone doesn't determine heat transfer without a temperature difference.

Work done against gravity is calculated as W = mgh, where m is mass (100 kg), g is gravitational acceleration (9.8 m/s²), and h is height (10 m). Therefore, W = 100 × 9.8 × 10 = 9800 J.

Static electricity is generated when two materials rub against each other, causing electrons to transfer and create an imbalance of charges. This is also known as the triboelectric effect, where friction creates stationary electric charges on surfaces.

For spherical mirrors, the radius of curvature (R) is twice the focal length (f). This relationship comes from the geometry of the mirror: R = 2f. Given f = 50 cm, we have R = 2 × 50 = 100 cm.

Millimeters of mercury (mm Hg), pascals (Pa), and bar are all units of pressure, which is force per unit area. The newton (N) is a unit of force itself, not pressure, making it the only option that doesn't measure pressure.

Wavelength is the spatial distance between two consecutive points in the same phase, such as crest-to-crest or trough-to-trough. It represents one complete cycle of the wave and is typically measured in meters.

Convex mirrors curve outward, causing light rays to diverge. This creates images that are always virtual (cannot be projected), erect (upright), and diminished (smaller than the object), regardless of the object's position.

The effective length of a bar magnet is the distance between its north and south magnetic poles. This is slightly less than the physical length because the poles are located slightly inside the ends of the magnet, not at the very tips.