Newtonian Mechanics and Forces

The contact forces represent the result of physical contact between two objects,one by which force is exerted and the other on which force is exerted.

When swimmer apply force on the water , then reaction force act on the man due to water. This force on the man drive man forward in the water.

Newton's first law of motion represents the qualitative measure of force.It states that:

First law of motion:

Maculae are the specialized mechanoreceptors within the utricle and saccule for the detection of static equilibrium, they make use of the hair cells to detect the movements of the otolithic membrane, the nerve impulses thus generated and transmitted along the vestibular branch of the cranial nerve to the central nervous system.

Maculae detect changes in the body with respect to gravity (static equilibrium) and in the movement in one direction (linear acceleration). So, the correct answer is (A).

Pressure is the force acting on a unit area of a surface it can be written as pressure  $= \dfrac{force}{area}$

Pressure is force acting on a unit area of a surface when force applied on object in a particular area of object exert pressure on it.

When a force acts vertically downwards or normal to the surface under consideration, it is called thrust.

The power output of a windmill is proportional to the cube of the wind velocity. Therefore, as wind velocity increases, the energy captured and the output of the windmill increase significantly.

We know that the fundamental quantities are mass, length and time. 

Speed, density and force are the derived physical quantities whereas time is the fundamental physical quantity.

There are only $7$ fundamental physical quantity out of which mass is a fundamental quantity.

Displacement, force, and velocity are vector quantities as they require direction as well as the magnitude for their representation but the kinetic energy is a scalar quantity as it does not require direction for its representation.