1. Chapter 2 Mechanical Equilibrium

2. What is a Force? Discuss (15 seconds)

3. Force A force is a push or pull that occurs as an interaction between two objects and results in a change on the objects state of motion. Net Force: The sum of all forces acting on an object is called the net force. Forces are measured in Newton units. 10N = 2.25lbs

4. What forces are we subjected to on a daily basis? Discuss (20 sec)

5. Forces GRAVITY! Friction

6. Force Vectors On paper, we represent forces with arrows. These arrows are called vectors and they have a specific length which represents it’s magnitude and the direction in which the arrow points represents the direction of the force. In this way vector quantities have both magnitude and direction.

7. ΣF=0 Σ is the capital letter sigma, and signifies “the sum of”. The letter F is how we denote Forces on paper. One can then infer that ΣF is the sum of all forces or as we previously stated the Net Force. When the net force acting on an object, the object is said to be in mechanical equilibrium.

9. Scalar Unlike vectors, scalars only have magnitude and no directionality. Time, area, and vomumes are all scalar quantities.

10. Normal Force/Support Force When an object is at rest on a surface, the weight of the object is pushing down on the object. The surface is pushing back up on the object. The upward force is called the normal force or support force. The two forces are equal in magnitude but opposite in direction, thus one is negative and the other is positive.

11. Equilibrium A non-moving object = Equilibrium An object in constant velocity in a straight line = equilibrium. Equilibrium is broken when net force changes The state of motion of the object. If an object in constant motion changes it’s velocity due to an outside force it is accelerating and thus undergoing a change in net force, thus disrupting its equilibrium.

12. Dynamic vs Static An object at rest is in static equilibrium. An object @ constant velocity in a straight line path is in dynamic equilibrium.

13. Adding Vectors Vectors pointed towards the same direction are added. Vectors pointed in opposite directions are subtracted. The sum of vectors is called the resultant. When vectors are at an angle of each other, things become a bit more complex.

14. Examples of aformentioned vector sums

15. Other points On the board: Perfect square diagonal resultant vectors. Tension angle increases/ strength of vector force increase as related to vector angles. Classwork begins with a bang; course workbook: Forces in Equilibrium Problems 1-5