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# Dynamics 1 - Forces

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### Dynamics 1 - Forces

1. 1. DYNAMICS - FORCES
2. 2. Objectives <ul><li>Describe the effect of balanced and unbalanced forces on a body </li></ul><ul><li>Describe the ways in which a force may change the motion of a body </li></ul>
3. 3. The Great Scientist Sir Issac Newton <ul><li>4 January 1643 – 31 March 1727 </li></ul><ul><li>Born in England and educated at Trinity College, Cambridge </li></ul><ul><li>Known as physicist, mathematician, astronomer, alchemist, inventor and philosopher </li></ul>
4. 4. The Great Scientist Sir Issac Newton <ul><li>Wrote the Philosophiae Naturalis Principia Mathematica in which he defined the 3 Laws of Motion in 1687 </li></ul>
5. 5. Dynamics <ul><li>Kinematics deals with the motion of the body without looking at what causes the motion of the body (displacement, velocity and acceleration) </li></ul><ul><li>In dynamics, we look at what causes motion. </li></ul>
6. 6. Dynamics Around Us <ul><li>Can you name some examples where you can observe the work of dynamics? </li></ul>
7. 7. Dynamics - Forces <ul><li>What is force? </li></ul><ul><ul><li>A push or pull that one object exerts on another which produces, or tends to produce motion, stops or tends to stop motion. </li></ul></ul><ul><ul><li>Vector (Remember how to represent a vector?) </li></ul></ul>
8. 8. Examples of Forces Weight Contact Force Tension Expansion Forces Upthrust Resistance Friction Centripetal Force Magnetic Force Electrostatic Force
9. 9. Dynamics - Balanced vs Unbalanced Forces <ul><li>Balanced vs Unbalanced forces </li></ul><ul><ul><li>Book not moving </li></ul></ul><ul><ul><li>Moving book </li></ul></ul><ul><ul><li>Is there a net force acting on the train when when it is moving at constant speed? </li></ul></ul><ul><li>Conclusion </li></ul><ul><ul><li>Balanced Force  F net = 0  No acceleration </li></ul></ul><ul><ul><li>Unbalanced Force  F net  0  Acceleration </li></ul></ul><ul><ul><li>Acceleration in direction of net force (for linear motion only) </li></ul></ul>
10. 10. Dynamics - Effect of Force on Motion <ul><li>Go to </li></ul><ul><ul><li>http://www.rlgreene.org/Illuminations/html/Dynamics/Demos/NewtonMotion1a.html </li></ul></ul><ul><ul><li>Observe how the motion of the body changes with the application of force in a different direction </li></ul></ul>
11. 11. Dynamics - Effect of Force on Motion <ul><li>Body moves in different ways depending on how force is applied. </li></ul><ul><ul><li>Velocity and net force in same direction </li></ul></ul><ul><ul><ul><li>Velocity increases in magnitude in original direction </li></ul></ul></ul><ul><ul><li>Velocity and net force in opposite direction </li></ul></ul><ul><ul><ul><li>Velocity decreases to zero, turns around and increases in magnitude in direction of acceleration. </li></ul></ul></ul><ul><ul><li>Velocity and net force at an angle </li></ul></ul><ul><ul><ul><li>Non-linear motion </li></ul></ul></ul><ul><ul><ul><li>If the speed is constant, is acceleration zero? </li></ul></ul></ul>