Organisms and Multiple Forces ```Name: Sergey M. Status: N/A Age: 50s Location: N/A Country: N/A Date: 2000-2001 ``` Question: At the same time every resting object on Earth is participating in tree (and maybe more?) different motions in Space with different speeds: a) in the direction of Earth's revolving around its axes with the speed about 8 km/s, b) in the direction of Earth's orbit around the Sun with the speed about 32 km/s and c) in the direction of our Solar Systems' trajectory around Galactic Center with the speed about 250 km/s. (I am sorry, that I don't remember exact numbers). As a biologist I have several questions regarding this complecs motions. 1) Can You describe, please, the common trajectory of Earth in Space during this simultaneous movements in relations to Sun and in relations to Galactic Center - how it will look (probably spirals) ? 2) How can we calculate the forces applied to any object on Earth which are generated during this simultaneous movement - are they strong or week and if they act at the same direction as Gravitational Force acts on any object on the Earth or in opposite direction? This question arises from my interest to calculate total forces applied on Earth to living organisms during their development and growth which they should overcome. For example, beside Gravitational Force, living beings also are under big atmospheric pressure - 20 m.t/ cm^2 . May be this movements add some additional forces? Replies: The earth undergoes many minor wiggles and wobbles due to many causes, tidal effects of the moon, the "off-center" of the center of mass, the gravity of other planets... Some of these are not even well understood. The important point is that gravity is the weakest of all forces, so its effect decreases rapidly with distance. Consequently, the only astronomical objects that have to be taken into account when considering gravity are: Earth itself, the Moon, and the Sun. The effect of other planets and celestial objects on things having small mass, like living organisms, is extremely small, and other "small effects" are much larger -- for example the change in atmospheric pressure, various types of electromagnetic radiation, the pressure of soil pressure, and many more. Vince Calder Sergey, In order to calculate the effective amount of force for any orbital motion, calculate mass of the object (the person) times the square of the speed, then divided by the radius of orbit. Let's consider a 100 kg person, just to make it simple. Rotation of the Earth: (100kg)(465 m/s)^2 / (6.37e6 m) = 3.4 Newtons = .764 pounds Orbit of Earth around sun: (100kg)(29,800m/s)^2 / (1.50e11 m) = 0.592 Newtons = .133 pounds A 100 kg man feels a weight of 980-Newtons, a force of 3.4-Newtons from Earth rotation, and 0.592-Newtons from Earth orbit of the Sun. As radius of the orbit increases, the effect will decrease significantly. There is no need to go beyond effects of the solar system. Dr. Ken Mellendorf Click here to return to the Physics Archives

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