section_path: Difficulties
section_name: Difficulties
paragraph_text: Difficulties
  
  Since accurate measurement is essential in many fields, and since all measurements are necessarily approximations, a great deal of effort must be taken to make measurements as accurate as possible. For example, consider the problem of measuring the time it takes an object to fall a distance of one metre (about 39 in). Using physics, it can be shown that, in the gravitational field of the Earth, it should take any object about 0.45 second to fall one metre. However, the following are just some of the sources of error that arise:
  
  Additionally, other sources of experimental error include:
  
  Scientific experiments must be carried out with great care to eliminate as much error as possible, and to keep error estimates realistic.