In the International System of Units (SI), what is the unit of force?

Introduction / Context:

This general knowledge physics question asks about the correct SI unit of force. Force is a fundamental concept in mechanics, defined as any interaction that can change the motion of an object. Using the correct unit is essential when applying Newton’s laws of motion, calculating weight, and solving a wide range of engineering and physics problems.

Given Data / Assumptions:

• Force is defined by Newton’s second law: F = m * a.
• Mass is measured in kilograms (kg) and acceleration in metres per second squared (m/s^2).
• The question provides several different physical unit names, only one of which is correct for force.

Concept / Approach:

By Newton’s second law, a force of 1 newton is defined as the force required to accelerate a mass of 1 kilogram at 1 m/s^2. This definition leads to the unit newton, symbol N, where 1 N = 1 kg * m/s^2. Pascal is the unit of pressure, watt is the unit of power, and Boyle refers to a scientist, not a unit. Therefore, among the given options, newton is the correct SI unit of force.

Step-by-Step Solution:

Verification / Alternative check:

Physics textbooks, engineering handbooks, and scientific calculators all use the newton as the standard unit for force. Weight calculations such as W = m * g give weight in newtons when mass is in kilograms and g is in m/s^2. Pressure is defined as force per unit area, with SI unit pascal where 1 Pa = 1 N/m^2, again reinforcing that newton is the unit of force.

Why Other Options Are Wrong:

• Pascal: SI unit of pressure, defined as 1 newton per square metre.
• Boyle: The name of a scientist associated with Boyle’s law in gas behaviour, not a physical unit.
• Watt: SI unit of power, defined as 1 joule per second, or 1 N * m/s.

Common Pitfalls:

Students sometimes confuse force and pressure, especially because both involve newtons in their definitions. However, force is a vector quantity measured in newtons, while pressure is scalar and measured in pascals. Others may confuse power with force, but power measures the rate of doing work in watts. Remember the basic relationships: F = m * a, P = W / t, and p = F / A, and associate newton with force, pascal with pressure, and watt with power.

Final Answer:

The SI unit of force is the newton.