Normal is the other half of an action-reaction pair
If a person is sitting on a chair , there must be a gravitation force acting in downward direction which is equal to the weight of that person . That means the person is exerting a force on the chair equal to its weight . But the person is not falling down the chair , because of newtons third law of motion .
There must be a counter force which is equal and opposite to the force exerted by the person on the chair , in order to make net force equal to zero and to make that man in stationary state ( no movement ) .That force is called Normal force which is been acted by the chair on the person .This implies Normal is the other half of an action-reaction pair
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Explanation:
It is given that,
Frequency of vibration, f = 215 Hz
Amplitude, A = 0.832 mm
(a) Let T is the period of this motion. It is given by the following relation as :



(b) Speed of sound in air, v = 343 m/s
It can be given by :




Hence, this is the required solution.
Answer:

Explanation:
From the question we are told that:
Distance 
Angle 
Force 
Generally the equation for magnitude of the stabilizing component of the brachialis force is mathematically given by



Air blows from one place to another because gases move from high-pressure areas to low-pressure areas
In simple words
it happens because of pressure differences.