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CHAPTER, ll Force AND PRESSURE, , POINTS TO GRASP, , Force : A push or a pull on an object is known as force., Push: It isan action of applyinga force on a body to keep it away from its position., Pull : It is an action of applying a force on a body a distance apart from a person, to bring it nearby the person., Magnitude of a force : This is called the quantity of force applied on somebody., The strength of the force ually expressed by its magnitude., , Direction of a force : The direction in which bod, moves on applying a force is, called the direction of a force., , Muscular force : The force resulting due to the action of muscles is known as, muscular force., , Change in state : A force when applied can bring about motion in a body at rest, and a body in motion can come to the state of rest. This is called change in state., Contact force : Since muscular force can be applied only when it is in contact with, an object, it is also called a contact force., , Frictional force or force of friction : The force responsible for changing the state, of motion of objects is frictional force. The friction arises whenever there is some, movement between the two surfaces in contact., , Non-Contact force : A magnet can exert a force on another magnet or magnetic, substances without being in contact with it. This is an example of a non-contact, force. Electric force is also a non-contact force., , Magnetic force : A force exerted by a magnet on a magnetic substance is called a, magnetic force., , , , , , . Electrostatic force : The force exerted by a charged body is known as electrostatic, , force., , . Force of gravity : The force of gravitation exerted by the earth is usually referred, , to as the force of gravity., , Force of gravitation : Every object in the universe, whether small or large, exerts, a force on every other object which is known as force of gravitation., , Weak force : Force of gravitation is a weak force, as we do not fee!, rapidly with increase in distance between the objects., , Pressure : The force acting on a unit area of a surface is called pressure., Atmosphere : The envelope of air around us is known as atmosphere., Atmospheric pressure : The pressure exerted by air in the atmosphere is known, as atmospheric pressure., , , , , , , , it decreases