Terminology

• velocity: a rapidity of motion or operation; swiftness; speed
• acceleration: increase of speed or velocity.
• acceleration due to gravity
• air resistance: the opposition of the atmosphere to forward movement;also called aerodynamic drag
• energy: the capacity for vigorous activity; available power.
• force: physical power or strenght possessed by a living being
• mass: a body of coherent matter, usually of undefinite shape (size)
• weight: the amount or quantity of heaviness or mass; (amount of an objects weighs)
• law of gravitation: a law stating that any two masses attract each other with a force equal to a constant (constant of gravitation) multiplied by the product of the two masses and divided by the square of the distance btween them.
• free fall: the hypothetical fall of a body such that the only force acting upon it is that of gravity.
• potential energy: the enrgy of a body or a system with respcet to the position of the body or the arrangement of the particles of the system.
• kinetic energy: the energy of a body or system wih respect to the motion of the body or of the oarticles in the system 
• gravity: the force of attraction by which terrestrial bpdies tend to fall foward the center of the earth
• momentum: force or speed of movement; impetus, as of physical object or course events.
• projectile: an object fired from a gun with an explosive propelling charge, such as a bullet, shell, rocket, or grenade.
• trajectory: the curve described by a projectile, rocket, or the like in its flight.