Plans for the Week and Assignments:
1. Wednesday(09/29): Intro. to Ch.5&6 - Newton's Laws and Applications.
HW: Read pages 144-162, and solve probs. 1, 5, 13, 15, 17, and 21 on
2. Thursday(09/30): Conical Pendulum, Amusement Park Rotor, and
Car on Banked Curve. HW: Solve probs. 29, 32, and 39 on pages 165-6.
3. Friday(10/01): Lab - The Conical Pendulum. HW: Process lab
data and solve application problems.
4. Monday(10/04): Post-Lab Discussion. HW: Write Abstract for
Lab report (due Tuesday).
5. Tuesday(10/05): Review Ch. 5&6 - Newton's Laws and Applications.
HW: Finish all review handouts.
6. Wednesday(10/06): TEST on Ch.5&6 - Newton's Laws and Applications.
HW: Go to website for notes on Ch.7 - Work and Energy.
Very Important: If you have any questions or miss a class, see me before
school (8:00 - 8:30 AM), during 7th hour, or after school. Best to send an
email to email@example.com.
WEBSITE NOTES: AP Physics, Ch.5&6. - Newton's Laws and Applications.
1. 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. This is known as the law of inertia.
2. 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 FNET = ma .
3. Law III: For every action force there is always an equal and opposite
4. 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.
5. The MKS unit of mass is the kilogram (kg), while the unit of weight is the
6. To change mass to weight, use the equation Fg = mg . This is the same as
F = ma , with g = 9.8 m/s2.
7. There are two kinds of mass, gravitational and inertial mass. They are
numerically equal but are determined in two different ways.
8. Friction is a force that opposes the motion of an object. It is electromagnetic
9. The force of friction is determined by multiplying the coefficient of friction
and the normal force, Ff = μFN .
10. The coefficient of friction is given by the Greek letter mu, μ . Normal means
11. The normal force is the contact force of one surface on another.
12. The net force is the vector sum of all forces acting on an object.
13. Static friction is greater than kinetic friction.
Newton's second law applied to a particle moving in uniform circular motion
states that the net force must be toward the center.
14. Uniform circular motion occurs when an acceleration of constant magnitude is
perpendicular to the tangential velocity and the object maintains a constant speed
but is accelerated toward the center of the circle.
15. This introduces the concept of centripetal acceleration, a = v2/r , and, by
Newton's second law, centripetal force, F = mv2/r .
16. The central force acting on an object that provides the centripetal acceleration
could be have its origin in the following: (i) the force of gravity (as in satellite motion),
(ii) the force of friction (as in a car rounding a curve), or (iii) a force exerted by a string
(motion in a horizontal circle).
17. In the case of motion in a vertical circle, the force of gravity provides the tangential
acceleration and part or all of the centripetal acceleration.
18. For the conical pendulum, the horizontal component of the tension in the string
provides the centripetal force.
19. In the case of a car rounding an unbanked curve, the force of static friction is the
20. When the curved roadway is banked at an angle, then the horizontal component
of the normal force is centripetal.
21. If a particle moves along a curved path in such a way that the magnitude and
direction of v change with time, the particle has an acceleration vector that can be
described with two component vectors.
22. The radial component vector arises from the change in direction of v , which is the
centripetal acceleration, a = v2/r .
23. The tangential component vector is based on the change in magnitude of v , and is
found with the derivative dv/dt .
24. The total acceleration can be found with the vector sum of these two accelerations
which occur at right angles, so we use the Pythagorean Theorem and inverse tangent.
25. 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 vector formula to use
(iv) use Algebra, Trigonometry, and/or Calculus to isolate the unknown
(v) substitute-in the given information and simplify.