Analyzing Gravity Thru Newton’s Three Laws of Motion (By F. Mendoza Jr)

First Analysis

In Galileo’s experiment, his main concern was the motion of balls as they rolled down an inclined plane or to be more specific, the body itself in motion. This is a different approach. The main concern here is the relation between two objects, the rider and the vehicle. Let us call this “a rider to vehicle relationship” or simply R2V. In this example, the rider is the man in the elevator and the vehicle is the elevator itself. The law of Physics stated that all bodies have the property of inertia. Theoretically, in an ideal environment, the property of inertia of bodies involved would be at minimal opposition (no external factors like air resistance, friction or gravitational field of a star, etc present), we assume then that the vehicle would not need a great amount of supply of energy to make it move. But still, due to the presence of inertia, the elevator would need a transition time to adjust itself from its original state at rest to that state of motion. This could explain why at the first one second of the man’s journey, the elevator traveled only a distance of 4.9 meters.

What about the rider? The man inside the elevator is in a standing position. The motion of the elevator is in upward motion in respect to the man. Initially, the body of the man is in a state at rest. Once the elevator moves upward, the man’s body would try to oppose that change in state. The result is that the man’s feet would try to press the elevator’s floor. But eventually, due to inertia, his body would also move upward along with the elevator.

What about if energy is taken away exactly after the first one second of the journey? Theoretically, the speed of the vehicle at the moment before the energy was suspended should be at 35.28 km per hour. Both the man and the elevator are now in a state of motion. The result is that both of them would be traveling at the speed of 35.28 km per hour, forever. The man’s feet still in contact with the floor but no longer pressing the floor. Any slight movement of any part of his body would change the states of circumstance of both the rider and the vehicle and there would be a drastic change in speed and direction of path of journey.
What about if the vehicle suddenly stop? The man’s body would still be in its state of motion, so, it would still continue at that state. The result is that the man might hit the ceiling of the elevator and could cause his death.

This analysis shows the motions of the rider and the vehicle and the effect of inertia in different situations. This also proved that this hypothetical example is valid and conforms to Newton’s First Law of Motion.

Second Analysis:

This time, let us analyze the weight of the rider. Weight, according to Newton, is the force due to the pull of gravity. Assume that there is really no pull of gravity, then, could it be possible that the rider achieve the similar effect of weight on earth on a vehicle speeding away in space?

Theoretically, the initial state of circumstance of both the rider and the vehicle were the same, both in a state at rest. Once the elevator move, the man’s body follows. The elevator’s floor supports the man inside the elevator. The feet of the man is in direct contact to the floor. The man’s body due to inertia would try to keep its state of circumstance. At the moment the floor moves upward, the man’s body would not move at once. The man’s feet would press the floor until the body adjusted itself to a state of motion. If both attained the equal states of motion, there is no longer a pressing effect between the man’s feet and the floor. If the speed of the elevator is in a progressive accelerating pattern, it could sustain the pressing effect of the man’s body toward the floor. Therefore, if the accelerating speed of the vehicle is at 9.8 meters per second per second, the effect would be a sustainable pressing effect similar to Newton’s force called weight. This pressing effect would be constant regardless of how long or far the vehicle travels or how fast it travels as long as the acceleration of the vehicle is constant.

This analysis shows that it is the acceleration of a vehicle that determines the weight of the rider. This also proved that this hypothetical example is valid and conforms to Newton’s Second Law of Motion.

Third Analysis :

In this hypothetical example, the pressing effect that the man experienced inside a moving elevator in space was assumed to be the same effect he would experience if he was standing on the earth’s surface. Theoretically, it was the elevator that was in motion and not the man who was simply standing inside it, so it is valid statement to declare that the rider was not really exerting a force (or voluntarily doing it), the same way as to the vehicle’s floor. But due to acceleration (motion of the vehicle) and inertia (the property of the rider’s body), both of them seems creating two opposing forces. The man thought that the floor was stationary and his weight was the one that pressing down the floor, but to an outside observer, it appeared that it was the elevator’s floor that was pushing the man upward. The action would be the accelerating motion of the vehicle along with the accelerating upward motion of the floor that causing the opposite reaction of the man’s body, pressing down of the floor due to inertia.

This analysis shows that acceleration and inertia could be two of the factors that are vital in creating gravity and not Newton’s perception that gravity was due to the attracting forces between bodies, each bodies trying to pull each other. This also proved that this hypothetical example is valid and conforms to Newton’s Third Law of Motion.

SELF-OPINION:

Newton perceived gravity as a natural force, a nature-given property of a body to attract another body. If each body has this same property, each would try to pull one another. The forces of attraction between these bodies determine the strength of gravity. This explained why the sun and the planets in the Solar System remain in their respective orbits due to gravitational attractions - each one pulling one another. It follows then that the neighboring stars and galaxies must be doing the same thing, each one pulling each other to balance the gravitational attraction in the Universe.

But Hubble’s discovery that galaxies are moving away from each other suggests that the Universe could be expanding. Therefore, Newton’s perception that gravity is a force of attraction could be false. This hypothetical example could be one good attempt to redefine gravity – it could be due to two factors, the acceleration of the moving vehicle and the property of inertia of the rider’s body. This idea suggests that gravity could not be a natural force that always present in the Universe. It could be a consequence or an event that is happening and continue to happen due to the fact that all bodies in the Universe are at motion. This is similar to Einstein’s suggestion that gravity could be a consequence of bodies moving in geodesics in a four-dimensional curved space-time. Therefore, Einstein was correct – gravity is not a force.

Now that we established this new assumption that gravity is not a force, the problem would be how to compromise this idea with what we commonly observe? Assuming, the same man in space is now standing on the surface of the Earth. If gravity is caused by the acceleration of the vehicle and the property of inertia of the rider, it follows then that the ground where the man is standing could also be traveling in an accelerated speed of 9.8 meters per second per second. This would imply that all points on the surface of the earth are moving away from its center, meaning, the Earth is blowing up like a balloon in a tremendous rate of expansion. This therefore, would become a ridiculous idea. No, it isn’t – it has to do with the expanding behavior of the Universe along with a different approach in dealing with the four-dimensional Space-Time.

SUB-TOPIC:
Inertia is the property of a body at rest to remain at rest and the tendency of the same body at motion to remain at motion. This indicates that “inertia”, as a property of a body is a resistance, to oppose a “sudden” change in state at rest or at the state of motion . There is an emphasize to the word “sudden” because any body has the ability to change its state of circumstance, according to how fast it can adjust (rate of inertia) or how much the strength of its inertia (mass of the body). This could be a new subject to discuss, if there are bodies with a faster rate of inertia although its amount of inertia is large (massive bodies) and vice versa.