Forces & Changing Shape
- For stationary objects, multiple forces have to be applied to change their shape
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Objects can change their shape by:
- Stretching
- Bending
- Compressing
- A combination of all three shape changes can also occur
Compression
- An object is compressed when forces act
- In opposite directions
- Towards the object
- An example of compression is placing a mass on top of a spring placed on a flat surface
- The two forces are:
- The weight of the mass on the spring
- The reaction force of the surface on the spring
The compression or stretching of a spring requires two forces
Stretching
- An object is stretched when forces act:
- In opposite directions
- Away from the object
- An example of stretching is placing a mass on the bottom of a spring hanging vertically from a rod
- The two forces are:
- The weight of the mass of the mass on the spring
- The tension in the spring
- These two opposing forces cause a tension force in the spring
Bending
- An object is bent when multiple forces act:
- In opposing directions
- At different points on the object
- An example of bending is a diving board bending when a swimmer stands at the far end
- The two forces are:
- The weight of the swimmer on the diving board
- The reaction force of the block on the dividing board
Forces on a diving board cause it to be bend when a swimmer stands on one end
More than one force on an object can cause it to bend