Explanation

First Law: Delta U = Q + W

Where W = work done ON the system

Delta U = -300 J (decreases)

W = +120 J (work done ON the system)

-300 = Q + 120

Q = -300 - 120

Q = -420 J

Negative sign means 420 J heat is released from the system / heat is transferred out of the system.

Last verified on 03-11-2026

Explanation

• Joule (J) is the SI unit of heat, work, and energy.
• One joule is equal to one newton-metre (1 J = 1 N·m).
• Watt is the SI unit of power.

Last verified on 09-11-2026

Explanation

• The instrument used to measure temperature is called a thermometer.
• A thermometer shows how hot or cold an object or place is.

Additional information:

• Barometer measures air pressure.
• Hygrometer measures humidity (moisture in air).

Last verified on 16-06-2026

Explanation

• The standard approximate value of Earth's gravitational acceleration is 9.8 m/s².
• It is represented by the symbol (g).
• Its value varies slightly with altitude and location.

Last verified on 09-11-2026

Explanation

An atom consists of three subatomic particles:

1. Protons (positively charged)
2. Neutrons (neutral)
3. Electrons (negatively charged)

Additional Information:

• A neutral atom has equal protons and electrons; imbalance creates ions.
• Discovered by John Dalton in 1808 (Atomic Theory).
• Cation = positive ion.
  Anion = negative ion.
• Isotopes = same element with different neutrons.

Last verified on 09-11-2026

Explanation

• Work done is equal to Effort (Force) x Distance.
• This is represented mathematically as 
• W=F⋅d.
• Where W is work, F is the force (or effort), and d is the distance over which the force is applied.

Last verified on 09-11-2026

Explanation

• The SI unit of speed is metre per second (m/s).
• Speed is the distance travelled per unit time.
• Formula: Speed = Distance ÷ Time.
• Common symbols: v
• Dimension: L T−1

Last verified on 09-11-2026

Explanation

Explanation

• Esophagus is a muscular tube connecting mouth to stomach.
• It allows food and liquids to pass for digestion.
• Part of the digestive system.
• Lined with mucous membrane to protect and lubricate food passage.
• Moves food using peristaltic movements (wave-like muscle contractions).

Last verified on 07-02-2026

Explanation

• Flagella are long, whip-like structures that help bacteria in movement (locomotion).
• They rotate like a propeller, enabling the bacteria to swim.

Last verified on 09-11-2026