Explanation

• When the temperature of a metallic conductor increases, its atoms vibrate more rapidly.
• These vibrations cause more frequent collisions between free electrons, decreasing their relaxation time.
• As relaxation time decreases, electrical resistance increases.

Last verified on 30-10-2026

Explanation

m = 800 kg

v = 54 km/h = 54 _ 1000 / 3600 = 15 m/s

d = 22.5 m

Work = Force x distance = Kinetic Energy

F = m_v^2 / 2_d

F = 800 _ 15^2 / 2 _ 22.5

F = 800 _ 225 / 45

F = 4000 N

Last verified on 30-10-2026

Explanation

Formula: Cmed = Er * Cvac

So Cvac / Cmed = 1 / Er

Last verified on 30-10-2026

Explanation

• Near the Earth's surface, acceleration due to gravity is approximately constant at 9.8 m/s².
• During free fall over a small height, the change in gravity is negligible.
• At very high altitudes, acceleration due to gravity decreases as the distance from Earth's centre increases.

Last verified on 30-10-2026

Explanation

• Infrared waves are used in night vision equipment.
• They detect heat emitted by objects.
• It allowing visibility in low-light conditions.

Last verified on 29-10-2026

Explanation

• The value of Planck's constant is 6.63 × 10⁻³⁴ Js.
• This constant is fundamental in quantum mechanics.
• It relating the energy of a photon to its frequency.

Last verified on 29-10-2026

Explanation

• Power is the dot product of force and velocity.
• The formula is P = F · v = Fv cosθ, where θ is the angle between force and velocity.
• When force and velocity act in the same direction, power is P = Fv.
• The SI unit of power is the watt (W), equivalent to one joule per second.

Last verified on 28-10-2026

Explanation

• Radian is the unit of plane angle.
• It was traditionally classified as a supplementary quantity in the SI system.
• One radian is the angle subtended at the centre of a circle by an arc equal in length to the radius.

Last verified on 28-10-2026

Explanation

• The slope of a momentum–time graph represents the rate of change of momentum.
• According to Newton's second law, the rate of change of momentum is equal to the net force acting on an object.
• The relationship is F = Δp / Δt, where p represents momentum and t represents time.
• A steeper slope indicates a greater net force, while a horizontal line indicates zero net force.

Last verified on 28-10-2026

Explanation

• Mass and Length are base quantities in SI units.
• Length SI Unit: meter (m)
• Mass SI Unit: kilogram (kg)

Additional information:

Base Quantities in SI System:

• Time (second)
• Electric current (ampere)
• Temperature (kelvin)

Last verified on 16-06-2026