Explanation

The mass of Earth is approximately 6.0 x 10^24 kilograms (5.98 x 10^24 kg).

This is a widely accepted scientific value, based on various measurements and calculations, including:

• Gravity measurements
• Satellite orbits
• Seismological data
• Planetary formation models

Explanation

• The shortest distance between two points is called displacement.
• Displacement is a measure of the straight-line distance between two points.
•  It is a vector quantity.

Key Point: The longest distance between two points is called the circumference (if the points are on a circle) or a diagonal (if the points are on a polygon or a rectangle).

Explanation

Neutral equilibrium is a state where the body is balanced, but the slightest disturbance will not cause it to return to its original position or topple over.

In this state, the center of gravity (CG) remains at the same height, regardless of the slight tilt or displacement.

Key Points: 

• A body is in unstable equilibrium after slight tilt if its center of gravity remains above the point of contact.
  
• A body is in stable equilibrium after slight tilt if its center of gravity remains above the point of contact.
  

Explanation

The melting point of ice at normal atmospheric pressure is 0 °C (zero degrees Celsius).

Key Points:

• 0 K (zero Kelvin) is equivalent to -273.15 °C, which is absolute zero, the lowest possible temperature.
• 100 °C is the boiling point of water at normal atmospheric pressure.

Explanation

The SI unit of acceleration is meters/second^2 (m/s^2 or ms^-2)

Acceleration (a) is defined as the rate of change of velocity.

Velocity is a vector quantity, and therefore acceleration is also a vector quantity.

Explanation

Newton's first law of motion is also called as Law of inertia.

• Inertia is the ability of a body by virtue of which it opposes a change.
  
• According to Newton’s first law of motion, an object will remain at rest or in uniform motion in a straight line
• unless acted upon by an external force.
  • The inertia of rest: When a body is in rest, it will remain at rest until we apply an external force to move it. This property is called inertia of rest.
  • The inertia of motion: When a body is in a uniform motion, it will remain in motion until we apply an external force to stop it. This property is called inertia of motion.

Explanation

Efficiency is the ratio of output to input, often expressed as a percentage.

It represents how much of the input energy is actually converted into useful output energy, with the rest being lost as waste or heat.

Key Points:

• Energy is the ability to do work.
• Work is the transfer of energy through a force applied over a distance.
• Power is the rate at which work is done or energy is transferred.

Explanation

Weight is a vector quantity.

Because it has both magnitude (amount of force) and direction (downward, towards the center of the Earth).

Explanation

Heat is a form of energy, specifically thermal energy, which is transferred from one body to another due to a temperature difference.

It is a type of kinetic energy, where the particles of a substance vibrate or move rapidly, generating heat.

Explanation

A body is in equilibrium when the net force acting on it is zero, and it is not changing its motion.

This means that the body is either at rest or moving with a constant velocity (uniform speed), but not accelerating.