Understanding Gravity's Influence

• Gravity is a pervasive force, working on both massive and minute scales, from routine to extreme events.
• Surfers and skiers use gravity as an acceleration force.
• Gravity acts on everything with mass, constantly accelerating objects towards the Earth's center at 32 feet per second squared.
• All objects with mass or energy produce gravity.
• Gravity attracts, governs, warps, shapes, makes, and takes all matter and mass in the universe.
• Gravity holds the solar system together and binds all matter in the universe.
• Two dice placed at rest in space will slowly come together due to gravity.

Pulling Power

• Gravity formed the sun and Earth through gravitational contraction and attraction of particles.
• Gravity's pulling power depends on mass and distance.
• Gravitational force is proportional to the product of the masses of the objects involved.
• Gravitational force is inversely proportional to the square of the distance between objects.
• Doubling the distance between two objects reduces the gravitational attraction to a quarter of its original strength.
• Gravity directs the motion and movement of all matter in the universe.
• Galaxies orbit each other, and clusters of galaxies orbit their common center of mass due to gravity.

Freefall

• Galileo discovered that objects with different weights fall at the same rate.
• All objects fall at the same rate regardless of mass, which can be demonstrated through freefall experiments.
• During freefall, objects experience a sensation of weightlessness, also known as zero G, though gravity is still acting upon them.

Cannonball

• Isaac Newton recognized that the same force causing an apple to fall also keeps the moon in orbit around the Earth.
• Newton's "Principia Mathematica" explained how a cannonball fired at sufficient speed could orbit the Earth.
• An object must be fired at 17,500 miles per hour to orbit Earth.
• The moon doesn't fall to Earth because it has sideways motion, resulting in an orbit.
• Earth is in a constant state of freefall around the sun due to gravity.
• Traveling through a straight-line tunnel from one side of the Earth to the other using only gravity would take 42 minutes, regardless of the path.

Einstein

• Albert Einstein determined that gravity is caused by massive objects bending space.
• Planets' orbits are a result of the curvature of space caused by massive objects.
• Orbits are actually objects traveling in a straight line through spacetime but the curvature of spacetime bends the path.
• Einstein's theory explained the orbit of Mercury, which Newton's math couldn't fully account for.
• Mass warps both space and time, creating spacetime.

Snowboarding

• Snowboarders experience fleeting moments of weightlessness due to gravity.
• The trajectory of a snowboarder is freefall determined by velocity and gravity.
• Escape velocity is the speed needed to escape Earth's gravity, about 7 miles a second or 25,000 miles per hour.
• Potential energy is stored energy, while kinetic energy is the energy of motion.
• Spacecraft use the gravitational pull of planets for a slingshot effect, gaining kinetic energy and speed.

ZeroG Flight

• Astronauts on long journeys must learn to live and work in environments with reduced gravity.
• Zero G flights simulate weightlessness through parabolic arcs.
• During a 0 G flight, passengers experience weightlessness because the plane and its contents are in freefall.
• Acceleration and gravity create the same sensation.
• Zero G flights prepare astronauts for space by simulating the absence of gravity.

Artificial Gravity

• Artificial gravity may help humans overcome the effects of weightlessness on long space trips.
• Long periods of weightlessness can lead to bone loss, muscle deterioration, and blood clots.
• Personal centrifuge systems are being tested to create artificial G-forces in space.
• Spinning a person in a centrifuge can impart the same G-force as Earth's gravity.
• Using a centrifuge for one hour a day could provide astronauts with a "gravity tonic."
• Mars has 3/8 the gravity of Earth, which would affect the speed and height of skiing.
• A person weighing 100 pounds on Earth would weigh 38 pounds on Mars.
• A person weighing 100 pounds on Earth would weigh 254 pounds on Jupiter.
• Moving Earth's orbit using a comet or asteroid over billions of years could save it from being engulfed by the sun.

Gravitational Waves

• Gravitational waves are ripples in space caused by changes in gravity.
• Any type of mass in motion generates a gravitational wave.
• Gravitational waves travel at the speed of light.
• Space in one direction makes you fatter, in the other direction, it squashes you.
• Massive cosmic objects such as black holes and spinning neutron stars can cause gravitational waves.
• Supernova explosions can also generate gravitational waves.
• The Laser Interferometer Gravitational-Wave Observatory (LIGO) detects gravitational waves using laser beams and mirrors.
• The goal of the LIGO is to detect gravitational waves from the Big Bang.