Using v² = u² - 2gh, where final velocity v = 0 at maximum height: 0 = (20)² - 2(10)h, so h = 400/20 = 20 m.

Water has specific heat capacity of 4186 J/(kg·°C), which is significantly higher than iron (~450), copper (~385), and aluminum (~900). This property makes water excellent for heat absorption and temperature regulation.

Velocity is a vector quantity with both magnitude and direction, unlike speed which is scalar. Velocity can be negative, and in circular motion, velocity constantly changes direction.

Using v² = u² - 2gh, where final velocity v = 0, u = 20 m/s, g = 10 m/s². Therefore, 0 = 400 - 20h, giving h = 20 m.

Newton's Second Law: F = ma, where acceleration is directly proportional to force and inversely proportional to mass.

Using F = ma, F = 2 × 5 = 10 N. This is a direct application of Newton's Second Law.

The visible light spectrum ranges from violet (shortest wavelength ~400 nm) to red (longest wavelength ~700 nm). Red light has the longest wavelength among visible light.

Electric potential is defined as work done per unit charge. SI unit is Joule/Coulomb = Volt. Option D (Watt/Ampere) also equals Volt but option A is more fundamental.

Using lens formula: 1/f = 1/u + 1/v. 1/15 = 1/30 + 1/v gives v = 30 cm. When u = 2f, image forms at 2f with magnification -1 (same size, inverted, real).

At sunset, light travels through a longer path in the atmosphere. Shorter wavelengths (blue) scatter more (Rayleigh scattering), leaving longer wavelengths (red) to reach the observer.