Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
74 Cards in this Set
- Front
- Back
|
FORCE |
A push or pull applied to an object that causes motion or a change in motion |
|
|
FORCE |
Mass x acceleration |
|
|
Reaction force |
Applied by an object's physical supports- keeps the object from moving in response to externally applied forces |
|
|
Gravity |
An external force |
|
|
Center of gravity (COG) |
The point in the body where the effect of the line of gravity is localized |
|
|
Stress |
Change in structure of a biological or non-biological material |
|
|
1. Tension 2. Compression 3. Shear |
Forces that cause stress |
|
|
Tension |
Forces pulling APART |
|
|
Compression |
Forces that act TOWARD each other |
|
|
Shear |
Parallel forces (Sliding across the surfaces) |
|
|
Strain |
Resultant deformation of stress (not necessarily permanent) |
|
|
Pressure |
Force per unit area |
|
|
Pressure |
Stress is directly related to.... |
|
|
Torque/moment |
The product of the distance of the point of application of a force from the fulcrum and the magnitude of the force
(Magnitude x distance between application pint and fulcrum) |
|
|
Fulcrum |
Point of support |
|
|
Lever arm |
That which makes up the distance from a fulcrum to the point of application of a force |
|
|
Torque |
The longer the distance from the fulcrum, the greater the ___________ for the same force. |
|
|
A body at rest tends to remain at rest and a body in motion in a straight line tends to remain in motion unless external forces act to change either of these states. |
Newton's first law of motion |
|
|
Inertia |
What causes a person to be pitched forward in a wheelchair when it comes to a sudden stop. |
|
|
Momentum |
Mass X velocity |
|
|
Velocity (speed) |
Distance per unit of time |
|
|
For every force of action, here is an equal but opposite force of reaction |
Newton's third law |
|
|
Direct current (battery powered devices- PWC) |
Current which is constant due to a steady unchanging, unidirectional flow of charge |
|
|
Voltage |
A measure of the work required to move a unit charge from one point to another OR potential difference between 2 terminals |
|
|
Volt |
Unit of voltage |
|
|
Resistance |
The measure of the tendency of a material to impede the flow of electrons through it. |
|
|
Low |
Resistance is ______ in good conductors. |
|
|
High |
Resistance is _____ in poor conductors. |
|
|
V=iR |
Ohm's Law |
|
|
The current flowing through the material |
The voltage across conducting materials is directly proportional to______________. |
|
|
Frequency (hertz) |
Cycles per unit time |
|
|
Kilohertz (KHz) |
Sound frequency is measured in_________. |
|
|
Applied outside force |
The only thing that can change momentum |
|
|
Amplitude |
Maximum departure of the value of an alternating current or wave from the average value. |
|
|
Power (watts) |
Rate at which work is done. |
|
|
Watts |
Volts x amperes |
|
|
Watt-hours |
Rate at which power is being used |
|
|
Cathode |
Positive (+) terminal |
|
|
Anode |
Negative (-) terminal |
|
|
Displacement |
The position of the body in space |
|
|
Translational movement |
All parts of the body move in the same direction, at the same time, for the same distance |
|
|
Rotational movement |
Direction,distance, and time of movement occur simultaneously but moves through an angle around an axis or fulcrum |
|
|
Static friction |
The force that must be overcome to start a body in motion |
|
|
Dynamic friction |
Friction during movement (decreases once the body is in motion) |
|
|
Current |
The net charge crossing a cross section of a conductor per unit of time- charge in motion-flow of electrons past a given point |
|
|
Amperes (i) |
Unit of measurement for current |
|
|
Alternating current (house current) |
A current that reverses its direction at regular intervals |
|
|
Larger |
In American Wire Gauge, the smaller the number, the _______ the wire. |
|
|
No. 14 |
The typical house wire is ______. |
|
|
No. 12 |
The smallest wore permitted for wall outlets is _______. |
|
|
16-20 |
___________gauge wire is typically used in battery operated devices. |
|
|
Stranded wire |
Smaller wires grouped together to make a larger, more flexible wire. |
|
|
Heat |
Current flowing through a wire causes_______. |
|
|
Ultrasound |
Sound waves that are too high in frequency to be heard by the human ear |
|
|
Infrared |
Signal sent by LED or laser diode |
|
|
1. Good conductors of heat and electricity 2. Bright luster 3. Can undergo deformation without breaking (ductility) 4. High mechanical strength |
Characteristics of metals |
|
|
Iron |
Most abundant metal on earth |
|
|
Steel |
An alloy of iron and carbon plus a small amount of other elements |
|
|
Aluminum |
Lightweight, non-ferrous metal with good electrical conductivity , corrosion resistance, good workability, and non magnetic |
|
|
Copper |
Corrosion resistant metal that had good strength and conducts better than all metals except silver |
|
|
Magnesium |
2/3 the weight of aluminum, high strength to weight ratio, corrosion resistant |
|
|
Titanium |
Advanced composite material composed mostly of carbon fiber |
|
|
1. Easily fabricated 2. Lightweight 3. Corrosion resistant 4. Electrically resistant 5. Transparent and can be colored 6. Good damper |
Advantages of plastic |
|
|
voltage drop (wasted power) |
Forcing too many amperes through a wire will cause a _______ ________. |
|
|
1. Low strength 2. Dimensionally unstable 3. Thermally unstable 4. Deteriorates 5. Odorous 6. Difficult to repair 7. Costly |
Disadvantages of plastics |
|
|
Composites |
Material that consists of elements and fibers in a matrix |
|
|
larger |
The _________ the wire, the lower the voltage drop. |
|
|
Inefficiently |
When there is a voltage drop, appliances work ___________ because the voltage at the beginning of he wire is higher than at the end causing it to work on a voltage lower than it was designed for. |
|
|
Black and white; red |
If a cable has 2 insulated wires, they are _______and_______. The 3rd is _______. |
|
|
Hot, neutral |
The black wire is always ______ and the white wire is _________ and connected to the ground at one point. |
|
|
Uninsulated copper; green with yellow stripe |
Ground wire is either _________ or _________ . |
|
|
Fuse |
A short piece of metal that melts when more than a predetermined amount of amperes flows through it. |
|
|
Thermal or magnetic or both |
Circuit breakers can be _______or_______. |
|
|
Circuit breaker |
Disconnects the load if it is overloaded |
