English

Centre of Mass>Acceleration of Centre of Mass

Advertisements

Topics

  • Introduction
  • The Fundamental Formula: A Weighted Average
  • Application to Continuous Bodies
Maharashtra State Board: Class 11

Introduction

Imagine a complex object, like a wrench thrown in the air, or a system of two planets orbiting each other. The object might be spinning or wiggling, but there's one specific point that moves predictably—its Centre of Mass (CoM).

The acceleration of the CoM is incredibly important because it tells us how the entire system moves under the influence of external forces.

Maharashtra State Board: Class 11

The Fundamental Formula: A Weighted Average

The acceleration of the Centre of Mass (\[\vec a_{cm}\] ) is the weighted average of the individual accelerations (\[\vec a_i\]) of every particle in the system, where the weight is the particle's mass (mi).

\[a_{cm}=\frac{m_1a_1+m_2a_2+\cdots+m_na_n}{m_1+m_2+\cdots+m_n}\]

Using mathematical notation (for a system of n particles):

\[a_{cm}=\frac{\sum_{i=1}^nm_ia_i}{\sum_{i=1}^nm_i}=\frac{\sum_{i=1}^nm_ia_i}{M}\]
  • M is the Total Mass of the system.

  • Σmiai is the vector sum of (mi\[\vec a_i\]) for all particles. According to Newton's Second Law (\[\vec F\] = m\[\vec a\]), this sum is equal to the Resultant Force (\[\vec F_{net}\]) acting on the system.

Maharashtra State Board: Class 11

Application to Continuous Bodies

For objects where mass is smoothly distributed (like a solid sphere or a rod), the summation becomes an integral:

\[a_{cm}=\frac{1}{M}\int adm\]

Test Yourself

Advertisements
Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×