1. Thursday(09/10): FCAT Diagnostic Test. HW: Complete Review of

Physics Handout.

2. Friday(09/11): Introduction to Forces (Ch.4), Newton's Laws,

Interactive Forces, Free-Body Diagrams, and Friction. HW: Read Ch.4,

pages 86-99 and solve prob. 59, 61, 64, 66, and 67 on page 113.

3. Monday(09/14): Forces in Two Dimensions (Ch.5) and Vector

Mathematics. HW: Read pages 100-111 and solve prob. 75, 76, 77, 78,

and 79 on page 114.

4. Tuesday(09/15): Deriving Equations for Forces on Objects with

Friction. HW: Read pages 118-139 and solve prob. 79, 83, 85, 90, and

91 on pages 141-2.

5. Wednesday(09/16): Lab experiment on Friction.  HW: Process Lab

data and plot graph.

6. Thursday(09/17): Post-Lab discussion. HW: Complete lab report

and write Abstract, due Friday.

7. Friday(09/18): Review I for Ch.4 & 5. All homework must be

HW: Complete Review of Forces Handout #1.

8. Monday(09/21): Review II for Ch.4 & 5. HW: Complete Review of

Forces Handout #2.

9. Tuesday(09/22):  TEST on Ch.4 & 5 - Forces in One and Two

Dimensions. HW: Go to web-site for notes on Ch.6 - Motion in Two

Dimensions.

1. A force is a push or a pull on an object. A force can act through physical

contact (contact forces) or at a distance (field forces).

2. All forces are vectors because they have both magnitude and direction.

A free-body diagram shows force vectors as arrows.

3. The unit of force in the MKS system is the Newton, named after Isaac

Newton (1642-1727).

4. A Newton is another name for a kg m/s². In CGS we use the Dyne as a

unit of force.

5. The four fundamental forces are: Gravitational, Electromagnetic, Strong

Nuclear, and Weak Nuclear.

6. Isaac Newton determined that the causes of motion are forces. This study

is known as Dynamics. Recall that Galileo (1564-1642) developed Kinematics.

7. We still have the five motion formulas from the study of kinematics. We

know them as: (a) Δx = v_avg·Δt , (b) v_avg = (v_i+v_f)/2 , (c) v_f = v_i + a·Δt ,

(d) v_f² = v_i² + 2a·Δx , (e) Δx = v_i ·Δt + ½a·Δt² .

8. Newton summarized all motion with his three laws. Law I: An object will

remain at rest or in a state of constant motion if the forces acting on it are

balanced. (Law of Inertia)

9. Law II: The acceleration of an object is directly proportional to and in the

direction of the net force, but varies inversely with the mass. From this law

we get the equation that F_NET = ma . (Law of Acceleration)

10. Law III: For every action force there is always an equal and opposite

reaction force. (Action-Reaction)

11. We can now state the difference between mass and weight. Mass is the

measure of the amount of matter in an object. Weight is the force of gravity

on the object.

12. The MKS unit of mass is the kilogram (kg), while the unit of weight is the

Newton (N).  1 kilogram weighs 9.8 Newtons, or 2.2 pounds at sea level.

13. To change mass to weight, use the equation F_g = mg . This is the same

as F = ma , with g = 9.8 m/s².

14. There are two kinds of mass, gravitational and inertial mass. They are

numerically equal but are determined in two different ways.

15. Friction is a force that opposes the motion of an object. It is a type of

electromagnetic force. The major causes of friction are surface conditions,

and the weight of the object.

16. The force of friction is determined by multiplying the coefficient of

friction, given by the Greek letter, μ, and the normal force, F_N . 

Therefore F_f = μF_N .

17. The normal force, F_N , is the contact force of one surface on another.

Normal means perpendicular. It is equal in magnitude but opposite in

direction to the force of gravity, F_N = F_g .

18. Friction helps us walk, write, and also keeps knots tied. Friction

hinders us when we try to push or pull a heavy object, operate

machinery, and slide across a rough floor.

19. Static friction is greater than, but sometimes equal to, kinetic

friction. This explains why it is usually harder to get an object to move,

than to keep it moving.

20. The net force is the vector sum of all forces acting on an object. If

two forces are acting in the same or opposite directions, use algebraic

addition to find the resultant.

21.  For forces acting at right angles to each other, use the Pythagorean

Theorem to find the magnitude of the resultant, and then the inverse

tangent function to get the direction.

22. And still, we need these steps to solve any problem in Physics:

(i) read the problem and identify the given variables

(ii) determine what you are asked to solve for

(iii) find the correct motion formula to use

(iv) use algebra to isolate the unknown

(v) substitute-in the given information and simplify.

ARCHIVES:  CHAP. 1     CHAP. 2&3