Gravitation

• Gravitation, also known as gravity, is the force of attraction between any two bodies
• All objects in the universe attract each other with a certain amount of force
• Gravity's range is infinite, but the effect becomes weaker as objects move away
• There are four fundamental forces in the universe:

  • Gravitational force
  • Electromagnetic force
  • Strong nuclear force
  • Weak nuclear force
• Gravitational force is the weakest force out of the four forces
• On an atomic level, gravitational force is considered weak
• The electromagnetic force is a type of physical interaction that occurs between electrically charged particles
• The electromagnetic force can be attractive or repulsive
• The strong nuclear force holds together quarks, the fundamental particles that make up the protons and neutrons of the atomic nucleus
• The weak nuclear force is the force existing between elementary particles responsible for certain processes to take place at a low probability
• The value of the universal gravitation constant (G) is 6.673*10^-11 Nm^2/kg^2
• Acceleration due to gravity (g) is calculated as F=Mg
• Newton's Law of gravitation states that every object in the universe attracts every other object by a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them
• The moon revolves around the Earth due to centripetal force, which is the force of gravity of the Earth
• When an object undergoes circular motion, it experiences a centripetal force given by the equation F=mv^2/r
• Acceleration due to gravity is constant at g = 9.8 m/s^2 during free fall
• The mass of an object is the measure of its inertia and is constant throughout the universe
• The weight of an object is the force of attraction of the Earth on an object and is given by the equation W=mg
• The weight of an object on the Moon is 1/6 times the weight on Earth
• Thrust is the force acting on an object perpendicular to the surface
• Pressure is thrust per unit area, with the SI unit being Pascal (Pa)
• The pressure exerted by a fluid in a container is transmitted undiminished in all directions on the walls of the container
• Archimedes' Principle states that the upward force exerted by a fluid on an object is known as upthrust or buoyant force
• If the density of an object is less than the fluid, it will float; if the density is greater, it will sink
• Relative density is calculated as Density of a substance / Density of water
• Kepler's laws of planetary motion describe the motion of planets around the sun
• Kepler's first law states that the orbit of a planet is an ellipse with the sun as its foci
• Kepler's second law states that the line joining the planets and the sun sweeps equal areas in equal intervals of time
• Kepler's third law states that the cube of a mean distance of a planet from the sun is proportional to the square of the orbital time period T