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Law of Acceleration: "A change in the acceleration of an object is directly proportional to the force
producing it and inversely proportional to its mass“

Law of Reaction: "For every action, there is always an equal and opposite reaction"

Friction & Sports

Friction: the force acting along two surfaces in contact which opposes the relative motion of one body
over the other is called force friction. It is independent of the area of contact.

Methods to reduce friction in sports: The most common methods used to reduce friction between
moving surfaces include polishing the surfaces, lubricating the surfaces, using ball or roller bearings
and streamlining

Types of Friction

Static Friction

STATIC DYNAMIC

Why is friction necessary for movement?

Friction is a force which is applied in a opposite direction and helps in maintaining the balance of
body.

Friction is the force that combats relative motion between the two surfaces that come in contact.
Friction always acts in the opposite direction of the applied force. Friction is the force that opposes
the relative of one surface over another. EX. Ball stops after covering a distance.

Static Friction: The opposite force that comes into play when one body tends to move over the
surface, but the actual motion has not yet stated.

OR

Is the friction that is present when two bodies are static. This kind of friction can stop from moving on
a path. Dynamic friction- The opposing for that comes into play when one body in actually moving
over the surface of another body.

Dynamic friction

Rolling friction- The opposing force that comes into play when one body is actually rolling over the
surface of another body. For example, hockey / cricket ball is hit.

Sliding friction- The opposing force that comes into play when one body is actually sliding over the
surface of the other body. For example-Ice skating