Force | General Awareness for SSC CGL PDF Download

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Force

It is an external push or pull which can change or tries to change the state of rest or of uniform motion. SI unit is newton (N) and CGS unit is dyne. 1 N = 10⁵ dyne.
If sum of all the forces acting on a body is zero, then body is said to be in equilibrium.

Four fundamental forces in nature:

• Gravitational force
• Electromagnetic force
• Weak nuclear force
• Strong nuclear force (the strongest of the four)

Centripetal Force

During circular motion, a force directed towards the center of the circular path acts on the body, known as centripetal force.
where, m = mass of the body.

Centrifugal Force

In circular motion, a force appears to act outwardly opposite to the centripetal force, called centrifugal force. This is an apparent or pseudo force.

Applications of Centripetal and Centrifugal Forces

• Cyclists incline from vertical to obtain the required centripetal force, slow down to take safe turns, and move on a larger radius path to balance reduced friction due to bending.
• Roads are banked at turns to provide the necessary centripetal force, with the normal reaction force component contributing to this force.
• Frictional force between vehicle tires and the road acts as centripetal force during a turn on a curved road.
• If a car exceeds the safe speed limit on a turn, the inner tires, experiencing a larger centrifugal force due to a smaller radius, may skid.
• When a bucket of water is revolved rapidly in a vertical plane, centrifugal force prevents water from falling out, even when inverted.
• Electrostatic force acts as centripetal force for the orbital motion of electrons around the nucleus.
• During the rotation of milk, lighter cream particles move towards the center while heavier milk particles move to the circumference, resulting in cream separation.
• The gravitational force between the Earth and the Sun acts as the centripetal force for Earth's revolution around the Sun.
• Torque is the product of force and the perpendicular distance from the axis of rotation, producing a rotational effect. It is a vector quantity.