# Tower Cranes

Topics: Force, Mass, Kilogram Pages: 4 (1390 words) Published: May 27, 2013
The Association of

PROFESSIONAL ENGINEERS AND GEOSCIENTISTS
of the Province of British Columbia PEACE RIVER BRANCH

Bridge Engineering Principles
The following is a basic overview of the principles involved in building, and testing, a Popsicle bridge. Because this document is aimed at a variety of age levels the content may be too basic or advanced for your group. If you have any questions about the content, or you would like some more advance content, please feel free to contact the Peace River Branch of the Association of Professional Engineers and Geoscientists and we will do our best to accommodate your needs.

Force
Force can be defined as that which causes a mass to accelerate. Force has common units of pounds force (lbs) or Newtons ⎜

Acceleration (F=M·A). In other words 1 Newton is the force required to accelerate 1 kilogram by 1 m/sec2, or 1 pound force is the force required to accelerate 1 slug by 1 foot/ sec2. You will notice that the imperial unit for force is pounds force and not just pounds. There is a common inaccuracy in our language that is only really important when talking about physics. The word weight truly refers to a force – this is why your weight on the moon is not the same as your weight on earth. To fully understand this we need to dissect the mathematical meaning behind the force term. Two components go into calculating a force; the first is mass, the second is acceleration. What is mass? Mass is the amount of stuff present in a given sample, lets say a person. A person’s mass will be the same whether on earth or the moon – in both places that person is made up of the same amount of stuff. Mass has two common units; kilograms (kg) and slugs. So a person might have a mass of 70 kg or 4.78 slugs. For the example of weight, or the downward static force exerted by an object, the acceleration of interest is the acceleration due to gravity. The acceleration due to gravity can be defined as the pull one object exerts on another....