Explanation

• The SI unit of force is the newton (N).
• 1 N = the force needed to accelerate 1 kg of mass by 1 m/s²
• Derived unit: N = kg·m/s²
• Named after Sir Isaac Newton
• Based on F = ma (Newton's second law)

The base units relevant to force are:

1. The metre, unit of length — symbol m
2. The kilogram, unit of mass — symbol kg
3. The second, unit of time — symbol s

Last verified on 09-11-2026

Explanation

• The First Law of Thermodynamics is also known as the Law of Conservation of Energy.
• It states that energy can neither be created nor destroyed; it can only be transferred or transformed from one form to another.
• For example, an electric heater converts electrical energy into heat energy.
• The mathematical expression is Delta U = Q - W, where Q is heat supplied and W is work done by the system.

Last verified on 09-11-2026

Explanation

• Battery is a device that converts chemical energy into electrical energy.
• Batteries work by using a galvanic cell.
• It is an electrochemical device made up of two electrodes and an electrolyte solution.

Last verified on 16-03-2026

Explanation

The energy of a photon is calculated using the formula E = hf, where:

• h = Planck’s constant
• f = frequency of the photon

This shows that photon energy is directly proportional to its frequency.

Last verified on 23-05-2026

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