Wednesday, October 27, 2010

What is the effect of moving the fulcrum?

A fulcrum is a term commonly used with levers, which are simple machines that help us lift and/or move heavy loads at the expense of smaller effort or force. 


One can think of a lever as a rigid bar or rod which is pivoted about a point known as a pivot or fulcrum. The load is located at one end of the lever, while the effort is applied from the other end. The relative distances of the load end and effort end from the fulcrum gives us the mechanical advantage of the lever. 


Mechanical advantage = length of effort arm / length of load arm


The closer the fulcrum is to the load end (as compared to the effort end), the lesser effort is required. That is, we prefer a large value of mechanical advantage. 


Now the location of fulcrum determines the mechanical advantage. If we move the fulcrum towards the load end, the length of load arm reduces, while the length of the effort arm increases. As a result, the mechanical advantage is more (and less effort would be required). If, on the other hand, we move the fulcrum towards the effort end, the length of effort arm will reduce and that of load arm will increase, resulting in a lower mechanical advantage and necessitating more effort to do the same amount of work. 


Hope this helps. 

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