Gravity is a force the attracts objects toward the Earth. It is one approximation that the gravitational force that attracts objects the mass towards each other at an excellent distances.

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(Note: heaviness on the Moon is a pressure that attracts objects toward the surface ar of the Moon.)

The equation because that the force of heaviness is F = mg, wherein g is the acceleration due to gravity. Units deserve to be designated in metric (SI) or English system. The equation additionally indicates the weight of an object (W = mg).

The significant feature that this force is the all objects fall at the very same rate, nevertheless of their mass. Heaviness on the Moon and on various other planets have different values that the acceleration due to gravity. However, the impacts of the pressure are similar.

Questions girlfriend may have actually include:

What is the gravity equation? What is the most outstanding properties of gravity? What is gravity elsewhere?

This lesson will answer those questions. Valuable tool: systems Conversion

Gravity equation

According to Newton"s legislation of universal Gravitation, gravitation is the force that attractive objects toward each other. Because that objects fairly close come the Earth, this force is dubbed gravity, and also its equation is:

F = mg


F is the pressure pulling objects towards the earth m is the mass of the thing g is the acceleration due to gravity; this number is a continuous for every masses of matter mg is the product of m times g

Note: For verification that the gravitational force amounts to the pressure of heaviness for objects close to Earth, check out Gravity constant Factors.

Acceleration as result of gravity

The acceleration because of the force of heaviness on earth is designated by g. Its value is:

g = 9.807 meters every second-squared (m/s2) in the metric or SI mechanism of measurement

g = 32.2 feet every second-squared (ft/s2) in the English system of measurement

Note: since most textbooks use g = 9.8 m/s2 and 32 ft/s2, we will also use the rounded-off variation in this lessons.

In the equation F = mg, you should use the exact same measurement system for mass, m, as you perform for g.

Note: part textbooks carelessly specify g together the acceleration of gravity. That is incorrect and also misleading, since gravity does no accelerate. The expression should be the acceleration due to gravity, which is correct description of g.

Care need to be taken in defining scientific terms.

Weight and also mass

The load of an object of a provided mass is the pressure of heaviness on that object:

w = mg


w is the weight in newtons (N) or pound-force (lb) m is the fixed in kilograms or pound-mass (lb-mass)

Note: there is often confusion worrying the designation that weight and mass.

Although a kilogram is an alleged to be a unit that mass, the is regularly used come designate weight. You need to be aware that load of 1 kg of fixed is w = 9.8 newtons.

Also, a pound is an alleged to it is in a force, yet is often referred to as a mass. The mass of 1 pound-force is 1/32 pound-mass.

Again, you have to be precise in stating scientific terms.

Weighing an object

You can find the load of things on a calibrated scale—usually through a feather resisting the pressure of the weight.

The massive of an object can it is in measured v a balance scale, compare with an item of a provided mass.

Objects fall at the same rate

The most outstanding properties of heaviness is the truth that every objects fall at the same rate—assuming the result of wait resistance is negligible. This is due to the fact that the acceleration as result of gravity, g, is a consistent for all objects, no issue what your mass.

This seems counterintuitive, because you would intend a heavy object to loss faster than an item that weighed less. But it is a fact. Try dropping two objects in ~ the same time, indigenous the exact same height, making sure they are heavy enough not to be affected by air resistance. Friend will check out they struggle the ground in ~ the exact same time.

(See Equivalence principle of gravity for more information.)

Gravity elsewhere

When girlfriend talk around gravity, you mean gravitation near the Earth. However, the exact same gravity equation holds for objects near the Moon or various other planets, except that the value of g is different. In those cases, you frequently tell wherein the gravity is, such as "gravity ~ above the Moon" or "gravity on Mars."

Gravity on the Moon

The force of heaviness on the Moon is roughly 1/6 of the on the earth for a given mass. Thus:

Fm = mgm


Fm is the force or load on the Moon m is the fixed of an item gm is the acceleration as result of gravity ~ above the Moon

The worth for gm is 1.6 m/s2 or 5.3 ft/s2.

Weight and mass on the Moon

The worth for gm is about 1/6 that the value for g top top Earth. Thus, things on the Moon would weigh about 1/6 that its weight on Earth.

Using a spring scale, if you sweet 60 kg (132 pounds) top top the Earth, you would certainly weigh only 10 kg (22 lbs) top top the Moon. However, making use of a balance scale on both Earth and also the Moon, her mass would certainly be the same.

Dropped objects

If you dropped two objects of various weights top top the Moon, castle would autumn to the ground at the same rate. Friend wouldn"t have to worry about the effect of air resistance, since there is no waiting on the Moon.

Since gm = g/6, the objects would loss at a slow rate.

(See heaviness Equations because that Falling Objects and then apply gm to acquire the different values.)


Gravity is the force that pulls objects towards the Earth. The is a special instance of gravitation. The equation because that the force because of gravity is F = mg, resulting in the reality that every objects loss at the very same rate, nevertheless of your mass. Gravity on the Moon and also gravity on various other planets have various values of the acceleration because of gravity, but the results of the force are similar.

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Resources and also references

Ron Kurtus" Credentials


Gravity Resources

Force that Gravity - Universe now Magazine

Earth"s gravity - Wikipedia

How does heaviness work? - just how Stuff Works

Standard gravity - typical value, as compared to variation due to position on earth - Wikipedia

International gravity Formula - sport of gravity v distance from equator - Geophysics dept. College of Oklahoma

I feeling "lighter" when up a mountain yet am I? - national Physics activities FAQ


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Top-rated books on an easy Gravity Science


Top-rated publications on progressed Gravity Physics


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