More Questions from Applied Mechanics

Definition of the SI unit of force What is the name of the SI unit of force defined as the force which produces an acceleration of 1 m/s^2 when applied to a mass of 1 kg?

Civil Engineering Applied Mechanics Difficulty: Easy
Choose an option
  • A
    Dyne
  • B
    Newton
  • C
    Joule
  • D
    Erg
  • E
    Pascal

Answer

Correct Answer: Newton

Explanation

Introduction / Context:Units in mechanics must be clearly distinguished between force, work/energy, and pressure. The International System of Units (SI) defines the unit of force via Newton’s second law.

Given Data / Assumptions:

  • Mass m = 1 kg.
  • Acceleration a = 1 m/s^2.
  • Use SI base units and derived units.

Concept / Approach:

From Newton’s second law, F = m * a. The derived SI unit of force is the Newton (N), where 1 N = 1 kg * 1 m/s^2. Other named units belong to different systems (CGS) or different physical quantities (energy or pressure).

Step-by-Step Solution:

Start with F = m * a.For m = 1 kg and a = 1 m/s^2, F = 1 kg * 1 m/s^2 = 1 N.

Verification / Alternative check:

Dimensional analysis: [Force] = M L T^-2; substituting kg, m, s reproduces the Newton unit dimensions.

Why Other Options Are Wrong:

Dyne and erg are CGS units (1 dyne = 1 g·cm/s^2; 1 erg = 1 dyne·cm). Joule is SI unit of work/energy, not force. Pascal is SI unit of pressure (N/m^2).

Common Pitfalls:

Confusing energy (Joule) with force; mixing SI with CGS unit names.

Final Answer:

Newton

Discussion & Comments
No comments yet. Be the first to comment!
Join Discussion