gravitational force

When dealing with the force of gravity between two objects, there are only two things that are important – mass, and distance. The force of gravity depends directly upon the masses of the two objects, and inversely on the square of the distance between them.

Fundamental force, also called fundamental interaction, in physics, any of the four basic forces—gravitational, electromagnetic, strong, and weak—that govern how objects or particles interact and how certain particles decay.

Newton’s Theory of Gravity states that every object in the universe pulls on every other object. Every object feels this force, so it is a universal force. The force is always attractive; it is always a pull, never a push. Picture the force of gravity as the tension in an imaginary rope between two objects.

In a collision, there is a force on both objects that causes an acceleration of both objects; the forces are equal in magnitude and opposite in direction. For collisions between equal-mass objects, each object experiences the same acceleration. The woman receives the forward force and the man receives a backward force.

The formula is F = G*((m sub 1*m sub 2)/r^2), where F is the force of attraction between the two bodies, G is the universal gravitational constant, m sub 1 is the mass of the first object, m sub 2 is the mass of the second object and r is the distance between the centers of each object.

Newton’s law of universal gravitation is usually stated as that every particle attracts every other particle in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

Earth’s gravity comes from all its mass. All its mass makes a combined gravitational pull on all the mass in your body. You exert the same gravitational force on Earth that it does on you. But because Earth is so much more massive than you, your force doesn’t really have an effect on our planet.

A thousand newtons of force is what you feel if a very muscular or rather fat person (weighing in at about 100 kg or 220 lbs) is standing on you. It is also the force needed to lift that person.

about 22 mph

Out into space Once at a steady cruising speed of about 16,150mph (26,000kph) in orbit, astronauts no more feel their speed than do passengers on a commercial airplane.

about 27½ miles per hourSo far, the fastest anyone has run is about 27½ miles per hour, a speed reached (briefly) by sprinter Usain Bolt just after the midpoint of his world-record 100-meter dash in 2009.

So, light-speed travel and faster-than-light travel are physical impossibilities, especially for anything with mass, such as spacecraft and humans. However, even a miniscule proton would require near-infinite energy to actually reach the speed of light, and humans haven’t figured out near-infinite energy quite yet.