III. PHYSICS TOPICS

 
  1. Inquiry, Reflection, and Social Implications
  2. Motions of Objects
  3. Forces and Motion
  4. Forms of Energy and Energy Transformations

 

Additional Sites for Physics

 

P3. Forces and Motion

High School

    a. P3.1 Basic Forces in Nature
    Objects can interact with each other by “direct contact” (e.g., pushes or pulls, friction) or at a distance (e.g., gravity, electromagnetism, nuclear).

    1. Physics Animations
      Provides good application applets to help students visualize the motion of objects to help them better apply their knowledge.
    2. Frank Potter's Science Gems
      Excellent site for student interaction with several concepts, including, force, motion, acceleration, gravity, velocity, etc... Includes several student activities where students are able to change the parameters. Contains many links to other sites on this subject.

    b. P3.2 Net Forces
    Forces have magnitude and direction. The net force on an object is the sum of all the forces acting on the object. Objects change their speed and/or direction only when a net force is applied. If the net force on an object is zero, there is no change in motion (Newton’s First Law).

    1. Net Force
      This site explains the nature of net force. It has drawings showing examples of net force acting on a textbook.
    2. Net Force - Animation
      This site allows the student to see how three forces act on an orange disk. Drag the heads of the arrows representing these forces to observe the effect on the net force.
    3. The Net Force
      The site explains why "Net Force" is important and how to find the net force.
    4. The Physics Classroom - Net Force
      This site explains the calculations of net force acting upon an object. The site shows examples of calculations used to determine net force.

    c. P3.3 Newton’s Third Law
    Whenever one object exerts a force on another object, a force equal in magnitude and opposite in direction is exerted back on the first object.

    1. LAW #3: Equal and Opposite New
      Imagine a rocket is being launched from the earth. Hot gases are pushed out from the bottom of the rocket as the rocket is thrust upward. The force of the gases pushing against the surface of the earth is equal and opposite to the force with which the rocket moves upward.
    2. Lesson 4: Newton's Third Law New
      A force is a push or a pull upon an object which results from its interaction with another object. Forces result from interactions!
    3. Newton's Third Law Applied to Aerodynamics New
      For aircraft, the principal of action and reaction is very important. It helps to explain the generation of lift from an airfoil. In this problem, the air is deflected downward by the action of the airfoil, and in reaction the wing is pushed upward.

d. P3.4 Forces and Acceleration
The change of speed and/or direction (acceleration) of an object is proportional to the net force and inversely proportional to the mass of the object. The acceleration and net force are always in the same direction.

  1. Frank Potter's Science Gems
    Excellent site for student interaction with several concepts, including, force, motion, acceleration, gravity, velocity, etc... Includes several student activities where students are able to change the parameters. Contains many links to other sites on this subject.

e. P3.5x Momentum
A moving object has a quantity of motion (momentum) that depends on its velocity and mass. In interactions between objects, the total momentum of the objects does not change.

  1. Momentum New
    The momentum of a particle is defined as the product of its mass times its velocity. It is a vector quantity. The momentum of a system is the vector sum of the momenta of the objects which make up the system.
  2. Virtual Labratory Momentum Applet New
    See the variables that affect momentum when a force is applied.
  3. The Physics Department - Mechanics, Momentum New
    Objects in motion are said to have a momentum. This momentum is a vector. It has a size and a direction. The size of the momentum is equal to the mass of the object multiplied by the size of the object's velocity. The direction of the momentum is the same as the direction of the object's velocity.

f. P3.6 Gravitational Interactions
Gravitation is a universal attractive force that a mass exerts on every other mass. The strength of the gravitational force between two masses is proportional to the masses and inversely proportional to the square of the distance between them.

  1. Physics Classroom - "Circular Motion and Planetary Motion"
    Newton's laws of motion and kinematic principles are applied to describe and explain the motion of objects moving in circles; specific applications are made to roller coasters and athletics. Newton's Universal Law of Gravitation is then presented and utilized to explain the circular and elliptical motion of planets and satellites.
  2. The Virtual Visitor Center - Gravitational Interactions
    The site explains the nature of gravitational interactions between two objects. This site explains several approaches to explain the nature of gravity: Quantum Gravity and the String Theory are explored.

    g. P3.7 Electric Charges
    Electric force exists between any two charged objects. Oppositely charged objects attract, while objects with like charge repel. The strength of the electric force between two charged objects is proportional to the magnitudes of the charges and inversely proportional to the square of the distance between them (Coulomb’s Law).

    1. Electric Charge and Coulomb's Law
      This site explains the nature of electric charge, the law of conservation of charge, electro static charging, and Coulomb's Law.
    2. Electrical Charge
      This is a School for Champions educational website.The site uses text and diagrams to explain the nature of electrical charges. The site has a mini quiz to check student's understanding.
    3. Physics4Kids - Coulomb Basics
      This site explains Coulomb's Law, one of the basic ideas of electricity in physics.

    h. P3.7x Electric Charges — Interactions
    Charged objects can attract electrically neutral objects by induction.

    1. Molecular Expression - Electricity and Magnetism
      Over 40 interactive Java tutorials can be found here that will support the study of physics. These include the effect of an electromagnetic field on a compass, cathode rays and Lenz's law.
    2. Physics 2000 - Electric Force Fields
      A basic explaination of electric force fields. Several Applets allow the user to explore how objects are affected by an electric field.
    3. Physics4Kids - Electric Field Basics
      The site explains electrostatic fields. The site explains how an electric field is created and how its strength can be measured. How capacitors store electrical charges is explained.
    4. The Physics Classroom - Charge and Charge Interactions
      Charge interactions and the influence of electric force on objects are explained at this site. The site also has a nice explaination of the methods of charging, and the nature of electircal force.

    I. P3.p8 Magnetic Force (prerequisite)
    Magnets exert forces on all objects made of ferromagnetic materials (e.g., iron, cobalt, and nickel) as well as other magnets. This force acts at a distance. Magnetic fields accompany magnets and are related to the strength and direction of the magnetic force. (prerequisite)

    1. Physics4Kids - Magnets
      This site explains how a magnet works and gives a good explaination of the different types of magnets.
    2. Physics4Kids - Magnetic Field Basics
      The site explains the difference between magnetic fields and electric fields. This site has everything you need to know about magnetic fields.

    j. P3.8x Electromagnetic Force
    Magnetic and electric forces are two aspects of a single electromagnetic force. Moving electric charges produce magnetic forces and moving magnets produce electric forces (e.g., electric current in a conductor.

    1. Build Beakman's Electric Motor
      See a very easy way for your middle or high school students to build and even take home a motor of their own for little money and easy to find materials.  Many links to similar sites and scroll down to the end for directions to build.  Note: Play with the motor yourself ahead of time, many materials can be adjusted from the suggested materials. (such as… ring magnets instead of rectangular, plastic cup for base instead of wood block, vary wire loop sizes by getting different dowel sizes instead of toilet paper roll, different gauge wire… many opportunities for discovery for students)
    2. How Stuff Works - Electric Motor
      A list of where electrical motors are used around the home and a diagram of an electric motor and it's parts and how they work. Continue on for two more pages about electric motors and their diagrams.

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