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Types of mechanical forces

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A force exerted on a body can cause a change in either the shape or the motion of the body.The unit of force in SI system is the Newton(N) and CGS system is dyne.No solid body is perfectly rigid and when force are applied to it,changes in dimension occur.such changes are not always perceptible to the human eye since they are negligible. For the example,The span of a bridge will sag under the weight of a vehicle and a spanner will bend slightly when tightening a nut. It is also important for civil engineers and designers to appreciate the effects of forces on materials.Together with their mechanical properties of the materials. There three main types of mechanical forces that can act on a body.They are 1)Tensile force 2) compressive force and 3) shear force
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What is center of gravity??

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Center of Gravity Defined

Have you ever heard someone say that one of the advantages of being short and stocky is that you're less likely to get knocked over? They might have even mentioned that it's because the short and stocky person has a lower center of gravity. The center of gravity (CG) of an object is the point at which weight is evenly dispersed and all sides are in balance. A human's center of gravity can change as he takes on different positions, but in many other objects, it's a fixed location.
Follow me through a quick experiment. You'll need the following:
  • A #2 pencil
  • A fine edge like a ruler or a credit card
  • A permanent marker
  • A ruler (if you don't have one, you may be able to eyeball it)
Step 1: Attempt to balance the pencil on the edge you have selected.
Balancing the pencil may take some trial and error. The point at which the pencil balances may not be where you first thought. If it begins to tip in one direction, move the pencil back slowly in the opposite direction until it will stay there on its own.
Step 2: Once the pencil is balanced, mark the location of the balancing point with a permanent marker.
Step 3: Measure the distance between the ends of the pencil and the balancing point you have marked. Are the two lengths equal? On my pencil, the length from the eraser to the balancing point was actually 1.25 inches less than the length from the pencil tip to the balancing point. Why would this be the case?
In our experiment, the balancing point was another word for the center of gravity of this pencil. In other words, if we cut the pencil in two at the mark we made in the experiment, the two parts would be equal in weight. However, they are not equal in length. As you may have already figured out, the metal piece that houses the eraser contributes more to the weight of the pencil, so the CG is closer to that side of the pencil.

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