INTRODUCTION/DEFINITIONS :
The force that causes this acceleration and keeps the body moving along the particular part is acting towards the center. This force is called the centripetal (meaning ‘centre-seeking’) force.
The motion of the moon around the earth is due to the centripetal force.
According to the second law of motion for a given force acceleration is inversely proportional to the mass of an object.
This force of attraction between objects is called the gravitational force.
Every object in the universe attracts attracts every other object with a force which is proportional to the product of their masses and inversely proportional to the square of the distance between them.
The value of G was found by Henry Cavendish (1731 – 1810) by using a sensitive balance. The accepted value of G is 6.673 × 10-11 Nm2kg-2.
The second law of motion that force is the product of mass and acceleration.
Mass of an object is constant and does not change from place to place.
The force of attraction of the earth on an object is known as the weight of the object.
Weight is the force acting vertically downwards. Here the force is acting perpendicular to the surface of the sand. The force acting on an object perpendicular to the surface is called thrust.
The effect of thrust on sand is larger while standing than while lying. The thrust on unit area is called pressure.
All liquids and gases are fluids. A solid exerts pressure on a surface due to its weight.
The upward force exerted by the water on the bottle is known as upthrust or buoyant force.
Weight of an object is the force due to gravitational attraction of the earth.
Archimedes principle, when a body is immersed fully or partially in a fluid, it experiences an upward force that is equal to the weight of the fluid displaced by it.
The force of attraction between two particles or objects is directly proportional to the product of the masses of the objects and inversely proportional to the square of the distance between them.
When an object falls towards the earth under the influence of gravitational force alone, then the object is in free fall.
The acceleration with which a body falls towards the earth is constant (= 9.8 m s-2) and independent of the mass of the body. Thus, all bodies fall with the same acceleration irrespective of their masses
Gravitational force with which a body A attracts another body B is equal in magnitude and opposite in direction to the gravitational force with which a body B attracts the body A.
All the planets revolve around the sun due to the gravitational force between the sun and the planets.
The atmosphere (envelope of gases) of the earth is possible due to gravitational force of the earth.
Rainfall and snowfall is possible only due to gravitational force of the earth.
Artificial and natural satellites revolve around the earth due to the gravitational force between the earth and the satellite