This equation is used to calculate force on a given mass of an object and its acceleration (or deceleration by using a negative value).  Also, a negative value can mean acceleration in the OPPOSITE direction.  F is the net force in newtons or 1 Kg * M/s².  That means if a mass of 1 kilogram (which is 2.204623 lb when at sea level on Earth) is decelerated by one meter per second (acceleration = -1),  it would take a force of 1 newton to stop it.  For British use, F is in the units of pounds and M is in units of slugs, which is a British unit for mass, and A is in units of ft/s².  Please note that WEIGHT is also a force, but is composed of MASS x ACCELERATION.  In place of A, use 9.803 if in m/s² or use 32.162 ft/s², which is the acceleration caused by Earth's gravity at sea level.^a a
 
 

    This is the most fundamental energy-related equation.  It is simply force x distance.  The cosine function is used ONLY if the force applied is not in the direction of the actual movement.  F is the force in Newtons.  D is the distance in meters.  W is the amount of work expressed in Newton-Meters.
 
 

    This is a fundamental energy-related equation that can handle varying amounts of force over a given distance. F is the force in Newtons.  D is the distance in meters. W is the amount of work expressed in Newton-Meters.
 
 

    This is the most fundamental spring-related equation.  It is simply distance x spring constant. X is the displacement from the spring's neutral position in meters. K is the "spring constant," which is a measure of the spring's stiffness. F is the force in Newtons.  To get a spring's k-value, take that spring and measure the force applied when stretched a known distance, and then just divide F by X.  Alternatively, you can stretch a spring until a designated force is reached, and then measure this distance in meters.  An easy way to do this is to suspend a spring from a fixed hook and hang a known mass onto this spring and measure the distance that the spring is stretched.  The equation here would be K=MG/X, where M is the mass in kilograms and G would be 9.803 (acceleration due to gravity), and X would be the displacement in meters.  Just be sure that you add the mass of any hooks and/or other fittings between the spring and the main mass.
 
 

    This is the most fundamental kinetic energy equation.  K is the kinetic energy (in joules) used.  M is the mass in kilograms.  V is the velocity in meters per second.
 
 

    This is the most fundamental kinetic energy equation.  K is the kinetic energy (in joules) used.  M is the mass in kilograms.  V is the velocity in meters per second  C is the speed of light, which is approximately equal to 3.0 x 10⁸ M/s..
 
 

    This is the most fundamental potential energy equation.  U is the potential energy (in joules) used.  M is the mass in kilograms.  Y is the vertical position in meters from which the potential energy would be zero.  For example, a heavy object would have twice the devastation when dropped from 50 meters as opposed to 25 meters due to having double the potential energy.
 
 

    This is the most fundamental potential energy equation.  U is the potential energy (in joules) used.  X is the position in meters from the neutral position of the spring.  For example, a heavy object would have twice the energy when suddenly released from a spring compressed by 0.2 meters as opposed to 0.1 meters due to having double the potential energy.  K is the "spring constant", which is equal to force divided by amount of displacement from the neutral position when that force is applied.  For example, if a spring is stretched 0.1 meters when 1 N of force is applied, the spring constant would be 1/0.1, in which K would equal 10.
 
 

    This is a basic power equation.  P is the power (in watts) used.  F is the force in Newtons.  V is the velocity in meters per second.  Please note that if F or V are varied over time, then calculus is required.
 
 

    This is the fundamental momentum equation.  P is the momentum (in kilograms x velocity in M/s) used.  M  is the mass in kilograms.  V is the velocity in meters per second.
 
 

    This is the fundamental impulse equation.  I is the impulse (change momentum).  P₁ is the momentum of one object hitting or being hit by another object. P₂ is the second object in this equation.  An example use of this equation would be when one car rams into another.
 
 

    This is a collision equation. V_f  is the speed immediately after an inelastic collision (in M/s).  M₁ is the mass (in kilograms) of one object hitting or being hit by another object.  V₁ is the speed of the first object in M/s.  M₂ is the mass of the second object in this equation.  V₂ is the speed of the second object in M/s.  An example use of this equation would be when onecar rams into another.  Please note that in a head-on collision, one vehicle must be assigned a negative velocity (due to moving in the opposite direction).
 
 

    This is set of equations for an elastic collision.  V_1f  is the speed the first object immediately after an elastic collision (in M/s).  V_2f  is the speed the second object immediately after an elastic collision (in M/s).  M₁ is the mass (in kilograms) of one object hitting or being hit by another object.  V₁ is the speed of the first object in M/s before the collision.  M₂ is the mass of the second object in this equation.  V₂ is the speed of the second object in M/s.  An example use of this equation would be when one car rams into another.  Please note that in a head-on collision, one vehicle must be assigned a negative velocity (due to moving in the opposite direction).