Physics
Solids have definite shapes.This is because

The forces of adhesion are less
The forces of adhesion are large
The forces of cohesion are very large
The forces of cohesion of the molecules within are very much less in them

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Physics
Railway tracks are banked on curves so that

No frictional force may be produced between the tracks and the wheels of the train
The train may not fall down inwards
Necessary centrifugal force may be obtained from the horizontal component of the weight of the train
Necessary centripetal force may be obtained from the horizontal component of the weight of the train

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