At the junction of the XVII and XVIII centuries, a scientist lived in Britain, Isaac Newton, who was very observant. It so happened that the view of the garden, where apples fell from branches to the ground, helped him discover the law of gravity. What force causes the fetus to move faster and faster to the surface of the planet, what are the laws of this movement? Try to answer these questions.
And if these apple trees, as Soviet propaganda had promised in their time, grew on Mars, what would this fall be like? Acceleration of free fall on Mars, on our planet, on other bodies of the solar system ... What does it depend on, what values does it reach?
Acceleration of gravity
What is remarkable about the famous Leaning Tower of Pisa? Slope, architecture? Yes. And from it it is convenient to throw various objects down, which was what the famous Italian researcher Galileo Galilei was doing at the beginning of the 17th century. Throwing down all sorts of gizmos, he noticed that in the first moments of a fall a heavy ball moves slowly, then its speed increases. The researchers were interested in the mathematical law by which a change in speed occurs.
Measurements made later, including by other researchers, showed that the speed of the falling body:
- in 1 second of fall it becomes equal to 9.8 m / s;
- in 2 seconds - 19.6 m / s;
- 3 - 29.4 m / s;
- ...
- n seconds - n ∙ 9.8 m / s.
This value of 9.8 m / s ∙ s was called the “acceleration of gravity”. On Mars (Red Planet) or another planet, is this acceleration the same or not?
Why is Mars different
Isaac Newton, who told the world what gravity is, was able to formulate the law of acceleration of free fall.
With the development of technologies that have raised the accuracy of laboratory measurements to a new level, scientists were able to confirm that the acceleration of gravity on planet Earth is not such a constant value. So, at the poles it is more, at the equator - less.
The answer to this puzzle lies in the above equation. The fact is that the globe, strictly speaking, is not exactly a globe. This is an ellipsoid slightly flattened from the poles. The distance to the center of the planet at the poles is less. And how it differs in mass and size from the globe Mars ... The acceleration of free fall on it will also be different.
Using Newton's equation and well-known data:
- the mass of the planet Mars - 6.4171 · 10 23 kg;
- the average diameter is 3389500 m;
- gravitational constant - 6.67 ∙ 10 -11 m 3 ∙ s -2 ∙ kg -1 .
It will not be difficult to find the acceleration of gravity on Mars.
g Mars = G ∙ M Mars / R Mars 2 .
g Mars = 6.67 ∙ 10 -11 ∙ 6.4171 · 10 23/3389500 2 = 3.71 m / s 2 .
To check the received value, you can look into any directory. It coincides with the table, which means that the calculation was made correctly.
How gravity acceleration is related to weight
Weight is the force with which any body with mass presses on the surface of the planet. It is measured in Newtons and is equal to the product of mass and acceleration of gravity. On Mars and any other planet, it, of course, will be different from the earth. So, on the moon, gravity is six times less than on the surface of our planet. This even created certain difficulties for astronauts who landed on a natural satellite. It turned out to be more convenient to move, imitating a kangaroo.
So, as it was calculated, the acceleration of gravity on Mars is 3.7 m / s 2 , or 3.7 / 9.8 = 0.38 from Earth.
And this means that the weight of any object on the surface of the Red Planet will be only 38% of the weight of the same object on Earth.
How and where does it work
We mentally travel through the Universe and find the acceleration of gravity on planets and other cosmic bodies. NASA astronauts plan to land on one of the asteroids in the coming decades. Take Vesta, the largest asteroid in the solar system (Ceres was bigger, but it has recently been transferred to the category of dwarf planets, "promoted").
g Vesta = 0.22 m / s 2 .
All massive bodies will become lighter by 45 times. With such a small gravity, any work on the surface will become a problem. A careless jerk or jump will immediately throw the astronaut a few tens of meters up. What can we say about plans for the extraction of minerals on asteroids. An excavator or drill rig will have to be tied to these cosmic rocks in the literal sense of the word.
And now the other extreme. Imagine yourself on the surface of a neutron star (a body with the mass of the sun, with a diameter of about 15 km). So, if in some incomprehensible way the astronaut does not die from the overwhelming radiation of all possible ranges, then the following picture will appear before his eyes:
g n.star = 6.67 ∙ 10 -11 ∙ 1.988510 30/7500 2 = 2 357 919 111 111 m / s 2 .
A 1 gram coin would weigh 240 thousand tons on the surface of this unique space object.