Gravity is the gravitational force exerted by the Earth (or another celestial body) on a much smaller object located nearby. Gravity in the Earth's gravitational field is a vector quantity, expressed as the product of gravitational acceleration (equal to the strength of the gravitational field) and the mass of the object:
$$\vec{F}=m\vec{g}$$
where,
m— mass of the object
g— gravitational acceleration.
Gravitational Acceleration
At sea level, the value of gravitational acceleration is considered:
$$\vec{g}\approx 9.80665\, \mathrm{m/s^{2}}$$
Gravitational acceleration is smaller at the equator than at the poles. Local gravitational anomalies (both in direction and magnitude) can be significantly influenced by Earth's topography (mountains) and geology (composition of the Earth's crust).
Gravitational force acting on an object on the Earth's surface
The formula for gravitational force acting on an object on the Earth's surface is given by Newton's law of gravitation.
$$F=G\frac{M \cdot m}{R^{2}}$$
where,
G— gravitational constant,
M— mass of the Earth,
m— mass of the object,
R— radius of the Earth.
Gravitational force acting on an object raised above the ground
The formula for gravitational force acting on an object raised above the ground:
$$F=G\frac{M \cdot m}{(R + h)^{2}}$$
where,
G— gravitational constant,
M— mass of the Earth,
m— mass of the object,
R— radius of the Earth,
h— the height (distance above the Earth's surface) of the raised object.
See also:
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