Conservation
of momentum
When two football players collide,
how can it be determined which player will be knocked backward ?
How can a lighter player overrun a heavier one ? It is through the
lighter player's momentum -- the product of his mass and velocity -- which
allows him to do so. With this law we may also see how cars act in
collisions.
When you push down on a bottle opener, the cap is lifted off. However, if you were to apply this force directly to the cap, the cap will not be lifted. The advantage of using the lever is that it can take the force that you out into it and give a greater force out. You are actually doing more work than it would take to lift the cap; however, it will feel easier because you will only need to use a fraction of the force. Other simple machines include the pulley, the wheel and axle, the screw, the wedge, and the inclined plane.
BACK TO THE TOP
Conservation
of energy
A rock sitting on the top of the cliff exhibits no
energy in its movement. However, if the rock were to fall from the
cliff, it would gain energy through its motion. The two major types
of physical energies are kinetic energy, the energy of motion, and potential
energy, stored energy which may be converted. The exchange between
kinetic and potential energies are equal and opposite in nature.
When we wind a watch it has potential to move. When the hands
actually move, that potential energy is being changed into kinetic energy.
The rock that was sitting on the top of a cliff had potential to
fall; as it falls and gets closer to the ground, that potential energy
is being changed into kinetic.
Law of heat
exchange
When two substances are mixed, they will reach some
median temperature that lies somewhere between the hot object and cold
object's temperature. The hotter object gives off heat while the
cooler one gains. This process is called heat exchange and the law
of heat exchange states that the heat lost by one substance equals the
heat gained by the other. In addition, heat may cause a state change.
If an object is at its melting point, it must overcome the heat of fusion
to change it from a solid to a liquid. If an object is at its boiling
point, it must have heat to overcom its heat of vaporization needed to
change it from a liquid to a gas.
Sample
problems and helpful links
| TOPIC | SAMPLE PROBLEMS | HELPFUL LINKS |
| CONSERVATION OF MOMENTUM | Pages 217-9, questions 1-12, 22-28, 34-40. | MR. BRUMLEY'S CHAPTER 9 REVIEW WORKSHEET |
| WORK AND MACHINE EFFICIENCY | Pages 241-4, questions 1-12, 18-28, 48-52. | MR. BRUMLEY'S CHAPTER 10 REVIEW WORKSHEET |
| CONSERVATION OF ENERGY | Pages 267-71, questions 1-19, 36-50, 55-59. | MR. BRUMLEY'S CHAPTER 11 REVIEW WORKSHEET |
| LAW OF HEAT EXCHANGE | Pages 295-297, questions 1-15, 21-28, 32-33. | MR. BRUMLEY'S CHAPTER 12 REVIEW WORKSHEET |