PMS 2026 GK Practice Set - 1000 One-Liners, Q51-100 (Physics: Motion, Forces, Energy, Waves & Electricity) Solved MCQs

Correct Answer: Law of Inertia

Newton's First Law is also called the Law of Inertia: a body stays at rest or in uniform motion unless acted on by an unbalanced force.

Correct Answer: Mass x Acceleration (F=ma)

Newton's Second Law states that force equals mass times acceleration (F = ma).

Correct Answer: For every action, there is an equal & opposite reaction

Newton's Third Law states that for every action there is an equal and opposite reaction.

Correct Answer: Velocity

Acceleration is the rate of change of velocity with time (it includes changes in direction as well as speed).

Correct Answer: Displacement per unit time

Velocity is displacement per unit time, so it has both magnitude and direction.

Correct Answer: Distance per unit time

Speed is distance travelled per unit time; unlike velocity, it has no direction.

Correct Answer: 9.8 m/s²

The acceleration due to gravity on Earth is approximately 9.8 m/s².

Correct Answer: Mass x Gravity

Weight equals mass times the acceleration due to gravity (W = mg).

Correct Answer: Kilograms (kg)

Mass is measured in kilograms (kg) in the SI system.

Correct Answer: Newton (N)

Force is measured in newtons (N) in the SI system.

Correct Answer: Force x Displacement in the direction of force

Work is force multiplied by the displacement in the direction of the force (W = Fd).

Correct Answer: Work

Energy is defined as the capacity to do work.

Correct Answer: Mass & velocity

Kinetic energy depends on mass and velocity (KE = 1/2 mv²).

Correct Answer: Mass, gravity & height

Gravitational potential energy depends on mass, gravity and height (PE = mgh).

Correct Answer: Work done per unit time

Power is the rate of doing work, i.e. work done per unit time (P = W/t).

Correct Answer: Watt (W)

The SI unit of power is the watt (W).

Correct Answer: Mass x Velocity

Momentum equals mass times velocity (p = mv).

Correct Answer: Total momentum remains constant

The law of conservation of momentum states that the total momentum of a system remains constant when no external force acts on it.

Correct Answer: Motion

Friction is a force that opposes the relative motion (or attempted motion) between surfaces in contact.

Correct Answer: Static, kinetic & rolling

The main types of friction are static, kinetic (sliding) and rolling friction.

Correct Answer: Force & extension in a spring

Hooke's Law relates the force applied to a spring to its extension (F = kx, within the elastic limit).

Correct Answer: Force per unit area

Pressure is force per unit area (P = F/A).

Correct Answer: 101.3 kPa

Standard atmospheric pressure at sea level is approximately 101.3 kPa (101,325 Pa).

Correct Answer: Fluids

Pascal's principle applies to fluids: pressure applied to an enclosed fluid is transmitted equally in all directions.

Correct Answer: Buoyancy in fluids

Archimedes' principle is about buoyancy: a body immersed in a fluid experiences an upward force equal to the weight of the fluid it displaces.

Correct Answer: Mechanical wave

Sound is a mechanical wave: it needs a medium (solid, liquid or gas) to travel through.

Correct Answer: 343 m/s

The speed of sound in air at about 20°C is approximately 343 m/s.

Correct Answer: Vacuum

Light travels fastest in a vacuum, at about 3 x 10^8 m/s, and slower in any material medium.

Correct Answer: Light bounces off a surface

Reflection of light occurs when light bounces off a surface instead of passing through it.

Correct Answer: Passes from one medium to another

Refraction occurs when light passes from one medium to another and changes speed, bending its path.

Correct Answer: Convex lens

A convex lens converges parallel light rays to a focus.

Correct Answer: Concave lens

A concave lens diverges parallel light rays, making them spread apart.

Correct Answer: Real or virtual images depending on object distance

A concave mirror forms a real or a virtual image depending on how far the object is from the mirror (virtual and upright when the object is inside the focal point).

Correct Answer: Virtual, upright & diminished images

Convex mirrors always form virtual, upright and diminished images.

Correct Answer: Hertz (Hz)

Frequency is measured in hertz (Hz), i.e. cycles per second.

Correct Answer: Two consecutive crests or troughs

Wavelength is the distance between two consecutive crests (or two consecutive troughs) of a wave.

Correct Answer: V=IR (Voltage = Current x Resistance)

Ohm's Law states that voltage equals current times resistance (V = IR).

Correct Answer: Ampere (A)

The SI unit of electric current is the ampere (A).

Correct Answer: Ohm (Ω)

The SI unit of electrical resistance is the ohm (Ω).

Correct Answer: Same in all components

In a series circuit the same current flows through every component.

Correct Answer: Same across all components

In a parallel circuit the voltage is the same across every component.

Correct Answer: Moving electric charges / current

A magnetic field is produced by moving electric charges, i.e. an electric current.

Correct Answer: Tesla (T)

The SI unit of magnetic field strength (flux density) is the tesla (T).

Correct Answer: Electric force between two charges

Coulomb's Law gives the electric force between two point charges.

Correct Answer: Easy flow of electric current

Conductors allow electric current to flow easily through them.

Correct Answer: Flow of electric current

Insulators resist the flow of electric current.

Correct Answer: Electrical energy

A battery converts stored chemical energy into electrical energy.

Correct Answer: Electrical energy

A generator converts mechanical energy into electrical energy.

Correct Answer: Increase or decrease voltage

A transformer is used to increase (step up) or decrease (step down) alternating voltage.

Correct Answer: Direction periodically

Alternating current changes its direction periodically (and its magnitude with it).