Explanation

• The SI unit of energy is the Joule (J).
• It is the unit of energy, work, and heat.

Additional information:

• 1 Joule (J) = 1 Newton × 1 meter
• Calorie – 1 cal = 4.184 J
• Kilowatt-hour (kWh) – 1 kWh = 3.6 × 10⁶ J
• Electronvolt (eV) – 1 eV ≈ 1.602 × 10⁻¹⁹ J
• Erg (CGS unit) – 1 erg = 10⁻⁷ J

Last verified on 17-01-2026

Explanation

• Earth’s gravity provides the force that keeps satellites in orbit.
• This gravitational force pulls the satellite toward Earth.
• The satellite’s forward motion makes it continuously fall around Earth rather than directly into it.
• Newton’s Law of Gravitation explains this gravitational attraction.

Explanation

Bernoulli’s principle is based on conservation of energy in flowing fluids.

P+1/2 ρv2+ρgh=constant

For airplane wings:

• P = Pressure
• ρ (rho) = Density of air
• v = Speed of air
• g = Gravitational acceleration
• h = Height
• Higher air speed → Lower pressure
• Lower air speed → Higher pressure
• Pressure difference between the upper and lower surfaces creates lift.
• Lift acts upward and helps the airplane fly

Explanation

• Inventor: Thomas Alva Edison.
• Country: United States.
• Practical incandescent bulb: 1879.
• Other contributions: Electric power, sound recording, motion pictures.
• Famous invention: Phonograph.

Last verified on 03-09-2026

Explanation

• Mercury is the closest planet to the Sun, followed by Venus.
• Called an inner planet because it orbits inside Earth’s orbit.
• Number of moons: 0 (Mercury has no natural satellites).
• Size: Smallest planet in the solar system.
• Nickname: Swift Planet, due to its fast orbit around the Sun (≈88 days per orbit).

Last verified on 17-03-2026