Gravity of the Earth

Gravity of the earth can be termed as the force by which the planet earth draws any object near the center. Apart from earth the gravitational force helps in keeping other planets following their orbits around the sun. The gravity of the earth is only denoted as “g”. However in SI units the acceleration is used to be expressed in m/s², or N/kg.

The average gravity of the earth is 9.80665 m/s² or 32.1740 ft/s².

The theory of gravitation was developed mainly due to the works of Isaac Newton and Albert Einstein.

Slight changes in the g can be observed as at the earth’s surface the g was 9.78 metres near the equator and 9.83 metres per second around the poles.

 What is the center of Gravity ?

Center of gravity can be defined as the imaginary point in a body of matter where the mass of the body would be concentrated. When a gravitational field is created with a uniform distribution it can be said that the center of mass and the center of gravity would be identical, if not the same. Earth’s center of gravity is believed to be 42 km from the center of the earth in the direction of the moon. This is somewhere around 1700km below the earth’s surface.

Newton’s law of Universal Gravitation.

This law usually states that any particle in the universe would attract another particle with a force which is directly proportional to the product of the mass of both the particles. It also stated that the force would be inversely proportional to the square of the distance  between the particle’s center. The equation of the theory is-

          F = G(m₁m₂ ) /  r  

In the above given equation F denotes the gravitational force between the two objects, r² denotes the distance between the particle’s center of masses, whereas G stands for the gravitational constant, m1 and m2 are the masses of both particles.

Gravitational Potential Energy

In simple words, gravitational potential energy can be defined as the energy stored in an object because of its portion on the earth’s surface. The formula used to find the Gravitational potential Energy is:-

Ep = mgh  or  PE = mgh

In the above formula, m stands for mass (kg), g stands for Gravitational Field Strength (N/kg), h stands for the height (m) and  Ep or PE denotes the gravitational potential energy in J. 

For example, a raised weight, river water on top of a waterfall waiting to fall, a book on a shelf before falling, etc.

These all were examples of Gravitational Potential Energy.

Some examples of Gravity of the Earth are:-

• A car always comes downhill without the driver putting the gas on. This happens because of the gravitational pull of the earth.

• We know all the plants stay in their orbits due to the gravitational pull of the sun. Likewise the moon follows its orbit around the earth

• The invisible force which keeps your feet on the ground while walking instead of you floating into the atmosphere is another example of gravity of the Earth.

• When a rock is pushed from a hilltop in a downwards movement, it keeps rolling down because of the gravitational pull of the earth.

• The force which causes any objects to fall from an elevated place is the Gravity of the Earth.

Conclusion

After the discovery of gravity the doors to outer space knowledge also grew, Gravity and its importance in our life can’t be denied. Gravity of the earth is the force which is pulling us near the earth’s surface. Newton’s and Einstein’s work regarding the theories of gravity opened our knowledge about the actual way of gravity’s working. The Gravitational potential energy which is stored inside an object is also a day to day occurrence in our lives. We learned that gravity is the force by which an object pulls, another object near it. Secondly, we found out that every object has its own gravitational pull based on its mass. There are an infinite number of examples of gravity around us which provide us knowledge about gravity, we just need to start observing things better.