Centre of Mass

• What is the definition of the centre of mass?

  The point where the weight acts
• Where is the centre of mass of a uniform regular solid located?

  At its centre
• Where is the centre of mass for a person standing upright?

  Behind the navel, roughly in the middle
• Where is the centre of mass of a sphere?

  At the centre
• For symmetrical objects with uniform density, where is the centre of mass located?

  At the point of symmetry
• How can the centre of mass of a shape be found?

  By using symmetry
• How does the position of the centre of mass affect stability?

  • Stable when centre of mass is above base
  • Topples if centre of mass is not over base
  • Wider base lowers centre of mass, increasing stability
  • Narrower base raises centre of mass, decreasing stability

  
• What is the characteristic of the most stable objects?

  Wide bases and low centres of mass

  
• In a uniform gravitational field, how do the centre of gravity and centre of mass compare?

  They are identical
• Does the centre of mass depend on the gravitational field?

  No, it does not depend on gravity
• How does the centre of gravity behave when an object is in space?

  It shifts towards the larger gravitational field
• What happens to the Moon's centre of gravity due to Earth's gravitational field?

  It is pushed closer to Earth

  
• What are the characteristics of the centre of mass?

  • Hypothetical point
  • Can lie inside or outside a body
  • Constantly shifts with body shape
  • Lower when leaning forward than upright