The formula for potential energy depends on the force acting on the two objects. For the gravitational force the formula is P.E. = mgh, where m is the mass in kilograms, g is the acceleration due to gravity (9.8 m / s2 at the surface of the earth) and h is the height in meters.

Thus, an apple falls from a tree because it feels the gravitational force of the Earth and is therefore subject to “gravity”. The acceleration g=F/m1 due to gravity on the Earth can be calculated by substituting the mass and radii of the Earth into the above equation and hence g= 9.81 m s-2.

The equation for gravitational potential energy is GPE = mgh, where m is the mass in kilograms, g is the acceleration due to gravity (9.8 on Earth), and h is the height above the ground in meters.

In symbols, the magnitude of the attractive force F is equal to G (the gravitational constant, a number the size of which depends on the system of units used and which is a universal constant) multiplied by the product of the masses (m1 and m2) and divided by the square of the distance R: F = G(m1m2)/R2.

In the first law, an object will not change its motion unless a force acts on it. In the second law, the force on an object is equal to its mass times its acceleration. In the third law, when two objects interact, they apply forces to each other of equal magnitude and opposite direction.

The laws are: (1) Every object moves in a straight line unless acted upon by a force. (2) The acceleration of an object is directly proportional to the net force exerted and inversely proportional to the object’s mass. (3) For every action, there is an equal and opposite reaction.

Newton’s First Law of Motion says that an object will remain in its state of motion unless acted upon by force. Essentially, this means that if an object is not moving, it will remain still until a force (a push or pull) acts on it.

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.

Einstein argued that gravity isn’t a force at all. He described it as a curvature of time and space caused by mass and energy. Their math, laid down in 10 equations, explained how gravity could move around objects via a warped reality, accelerating without ever feeling any mysterious Newtonian forces.

Einstein postulated three ways this theory could be proved. One was by observing the stars during a total solar eclipse. The sun is our closest strong gravitational field. Light traveling from a star through space and passing the sun’s field would be bent, if Einstein’s theory were true.

Yet most researchers think general relativity is wrong. incomplete . After all, the other forces of nature are governed by quantum physics; gravity alone has stubbornly resisted a quantum description. The fix is dark matter, particles invisible to light but endowed with gravity.

General relativity has also been confirmed many times, the classic experiments being the perihelion precession of Mercury’s orbit, the deflection of light by the Sun, and the gravitational redshift of light. Other tests confirmed the equivalence principle and frame dragging.

The predictions of general relativity in relation to classical physics have been confirmed in all observations and experiments to date. Although general relativity is not the only relativistic theory of gravity, it is the simplest theory that is consistent with experimental data.

General Relativity Failed to Be Quantized Quantum mechanics can be said to be the cornerstone of modern physics. For every physical field theory it should be possible to formulate it as quantum field theory. This indicates again that general relativity can hardly be an absolutely correct theory of gravitation.

Physicists have verified a key prediction of Albert Einstein’s special theory of relativity with unprecedented accuracy. Experiments at a particle accelerator in Germany confirm that time moves slower for a moving clock than for a stationary one.

Space travel induces bodily changes that are remarkably similar to growing old, providing a unique way to boost medical research. Spaceflight influences biology in dramatic ways, and people in space appear to experience the effects of aging faster than people on Earth.

More than 100 years ago, a famous scientist named Albert Einstein came up with an idea about how time works. He called it relativity. This theory says that time and space are linked together. Einstein also said our universe has a speed limit: nothing can travel faster than the speed of light (186,000 miles per second).

Travelling in time might sound like a flight of fancy, but some physicists think it might really be possible. BBC Horizon looked at some of the most promising ideas for turning this staple of science fiction into reality.

TARDIS (“Doctor Who”) Perhaps the most famous of time machines, the TARDIS (Time And Relative Dimension In Space), which is disguised as a police phone booth, allows Doctor Who and his companions to jump across eras on planet Earth.

Time machines It is generally understood that traveling forward or back in time would require a device — a time machine — to take you there. Time machine research often involves bending space-time so far that time lines turn back on themselves to form a loop, technically known as a “closed time-like curve.”