• Forces
    Use the link all the way at the bottom of the page for the lab where you need to use "Free Body Diagram".
    2nd Lab Link

    There are 4 fundamental forces that have been identified. In our present Universe they have rather different properties.

    Properties of the Fundamental Forces

    • The strong interaction is very strong, but very short-ranged. It acts only over ranges of order 10-13 centimeters and is responsible for holding the nuclei of atoms together. It is basically attractive, but can be effectively repulsive in some circumstances.

    • The electromagnetic force causes electric and magnetic effects such as the repulsion between like electrical charges or the interaction of bar magnets. It is long-ranged, but much weaker than the strong force. It can be attractive or repulsive, and acts only between pieces of matter carrying electrical charge.

    • The weak force is responsible for radioactive decay and neutrino interactions. It has a very short range and, as its name indicates, it is very weak.

    • The gravitational force is weak, but very long ranged. Furthermore, it is always attractive, and acts between any two pieces of matter in the Universe since mass is its source.

    Newton's Discovery!

    Newton discovered the laws of motion and forces, but the most important thing to remember is:

     It takes two to tango!  

    All of his laws are about the interaction of two objects.  An object cannot act upon itself.

    Here are his laws

    Newton's First Law:

    I. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. 

    Translation:  Something will continue to do what it does unless something stops it.

    Newton's Second Law:

    II. The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector.

    Translation: A force is made up of the components of mass and acceleration.  The relationship between mass and acceleration is magnified to create a force.

    Always remember this: If it hurt, then you experienced a force.  Force is measured in "Newtons".

    Newton's Third Law:

    III. For every action there is an equal and opposite reaction.

    Translation: When the Hulk tries to pickup Thor's hammer he can't.  The force he exerts to lift the hammer is also placed on the floor through his feet.  If one object is overcome by the action, it gives way to the object with the greater force.  In Hulk's case, it is the floor that loses.