# Descriptive Essays

## Descriptive Essays

• Submitted By: ridaynakhate
• Date Submitted: 03/14/2009 3:31 AM
• Category: Science
• Words: 898
• Page: 4
• Views: 1642

Aim: to observe the change in the number of oscillations before the cantilever reaches its mean position.with the change in the length of the cantilever exposed to the force applied.

Hypothesis: the greater the length of the cantilever exposed the greater the number of oscillations before the cantilever reaches its rest position.

Background:

Levers:
Simple machine used to amplify physical force. All early people used the lever in some form, for moving heavy stones or as digging sticks for land cultivation. The principle of the lever was used in the swape, or shaduf, a long lever pivoted near one end with a platform or water container hanging from the short arm and counterweights attached to the long arm. A man could lift several times his own weight by pulling down on the long arm.

First class lever
A first-class lever is a lever in which the fulcrum is located between the input effort and the output load. In operation, a force is applied (by pulling or pushing) to a section of the bar, which causes the lever to swing about the fulcrum, overcoming the resistance force on the opposite side. The fulcrum may be at the center point of the lever as in a seesaw or at any point between the input and output. This supports the effort arm and the load.

Second class lever
In a second class lever the input effort is located at the end of the bar and the fulcrum is located at the other end of the bar, opposite to the input, with the output load at a point between these two forces.

Third class lever
For this class of levers, the input effort is higher than the output load, which is different from second-class levers and some first-class levers. However, the distance moved by the resistance (load) is greater than the distance moved by the effort. Since this motion occurs in the same length of time, the resistance necessarily moves faster than the effort. Thus, a third-class lever still has its uses in making certain tasks easier to do. In third class...