Which one of the following correctly defines the unit of force known as 'Newton'?

Correct Option

The correct option is

The force required to accelerate a mass of 1 kg by 1 m/s².

Explanation

The Newton (symbol: N) is the derived unit of force in the International System of Units (SI). It is defined based on Newton's Second Law of Motion, which establishes the relationship between force, mass, and acceleration ($F = m \times a$).

Option Analysis:

• The force required to accelerate a mass of 1 g by 1 cm/s². is Incorrect: The force required to accelerate a mass of 1 g by 1 cm/s² is defined as 1 Dyne. This is the unit of force in the CGS (Centimetre-Gram-Second) system.
• The force required to accelerate a mass of 1 kg by 1 cm/s². is Incorrect: This option mixes SI units (kg) with CGS units (cm/s²). A force accelerating 1 kg by 1 cm/s² equals 0.01 Newtons.
• The force required to accelerate a mass of 1 kg by 1 m/s². is Correct: By definition, 1 Newton is the force required to accelerate a mass of 1 kilogram at a rate of 1 meter per second squared.
  Mathematically: $1 \text{ N} = 1 \text{ kg} \times 1 \text{ m/s}^2$.
• The force required to accelerate a mass of 100 kg by 1 m/s². is Incorrect: The force required to accelerate a mass of 100 kg by 1 m/s² is equal to 100 Newtons.

Key Takeaway:
The Newton is the SI unit of force, defined as the force needed to accelerate a one-kilogram mass by one meter per second squared ($1 \text{ N} = 1 \text{ kg} \cdot \text{m/s}^2$).