Explanation

• An electric fan uses electrical energy to rotate its blades, producing mechanical motion.
• This mechanical energy helps in circulating air to provide cooling.

Last verified on 07-11-2026

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

Newton's second law relates force, mass and acceleration.

Acceleration = Force ÷ Mass = 20 ÷ 5 = 4 m/s².

Last verified on 07-11-2026

Explanation

• Inertia is the resistance of an object to a change in its state of motion.
• Greater mass means greater inertia.

Last verified on 07-11-2026

Explanation

• The direction of velocity continuously changes during circular motion.
• Centripetal acceleration acts toward the centre of the circular path.
• Constant speed does not mean constant velocity.

Last verified on 07-11-2026

Explanation

• The product of mass and velocity is known as momentum. P = MV
• If m is an object's mass and v is its velocity (also a vector quantity), then the object's momentum p is: p=mv
• It is a vector quantity.
• It having both magnitude and direction.
• Common symbols: p, p
• SI unit: kg⋅m⋅s−1
• Dimension MLT^−1

Last updated on 09-03-2026

Explanation

• The unit of pressure is N/m² (Newton per square meter).
• It is also called Pascal (Pa).
• Pressure means force applied per unit area.
• Higher force or smaller area increases pressure.

Last verified on 17-06-2026

Explanation

• Halogens belong to Group 17 (VIIA) of the periodic table.
• They are located in different periods: fluorine (2), chlorine (3), bromine (4), iodine (5), astatine (6) and tennessine (7).
• They have seven electrons in their outermost shell.

Last verified on 07-11-2026

Explanation

• Acids react with carbonates to produce salt, water and carbon dioxide gas.
• Effervescence (bubbling) occurs due to the release of carbon dioxide.
• Example: Hydrochloric acid reacts with calcium carbonate to form calcium chloride, water and carbon dioxide.

Last verified on 07-11-2026

Explanation

• Alexander Graham Bell is credited as the inventor of the telephone.
• He was awarded the first successful patent for it.
• The telephone was invented in 1876.
• Bell made the first-ever telephone call to his assistant Thomas Watson.

Last updated by NA on 06-11-2026