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ST Science midterm
weeks 1_5
Question | Answer |
---|---|
Work (TQ) | expanded energy in order to accomplish something |
Work in Physics | expended energy is a force applied to an object is to moved, and the accomplishment is that the object moves a distance |
Formula for Work (TQ) | force x distance |
Joule (TQ) | the coventional unit for work and energy |
Joule | a metric unit for work and is defined as a force of one newton acting over a distance of one meter, where the force and the distance moved lie in the same direction |
Work VS Energy | in order to do work, an object must have energy in order to have energy, an object must have work done to it. |
Power | if a 10-newton force is applied to an object, moving it 10 meters in 10 seconds, the person has done 100 joules of work |
Formula for Power | work divided by time |
Unit for Power | is watt |
How many watts of power in one horsepower | 746 |
THE AVERAGE HORSEPOWER A NORMAL HUMAN CAN GENERATE OVER A FEW MINUTES | one third, one tenth of horsepower for any greater length of time |
CONSERVATION OF ENERGY | throughout the entire universe, there is a fixed amount of energy and it will never change |
CONSERVATION OF ENERGY | energy cannot be created or destroyed; it can only be changed from one form of energy to another |
4 TYPES OF SIMPLE MACHINES | 1)inclined plane 2)lever 3)wheel and axle 4)pulley |
INCLINED PLANES | useful when attempting to lift something that is very heavy |
INCLINED PLANES | requires less force, although the distance up the ramp is greater than the distance straight up into the truck |
WEDGE | an inclined plane that can be moved |
LEVER | a simple machine that consists of a rigid bar supported at a point known as the fulcrum |
LEVER | effort force is applied at one point on the lever in order to move an object, known as the resistance force, located at some other point on the lever. |
CLASS-ONE LEVER (TEETER-TOTTER) | levers in which the fulcrum is somewhere between the point of applied force and the point of exerted force |
CLASS-ONE LEVER (TEETER-TOTTER) | consist of an effort arm where force is applied by the user, a pivot point called the fulcrum, and a resistance arm where the object to be lifted or moved is placed |
CHARACTERISTICS OF A CLASS-ONE LEVER | fulcun in the middle, effort on one side, resistance (load force)on the extreme side |
SECOND CLASS LEVER | is a lever in which both the effort and resistance forces (load force)are on the same side of the fulcrum, with the resistance force between the fulcrum and effort force |
CHARCATERISTICS OF A SECOND CLASS LEVER | fulcrum on one end, load force (resistance)in the middle, effort force o the other end (extreme side) |
WHEELBARROW (2ND CLASS) | fulcrum is the wheel, the resistance (load force) is the dirt, and the effort is the handle |
THIRD-CLASS LEVER | has both forces on the same side of the fulcrum, but in this class, the resistance force (load force)is farther away from the fulcrum than the effort force |
Characteristics of Third-Class Lever | fulcrum in on side, load force (resistance) opposite extreme side |
Speed | The distance an object travels during a particular time interval |
Velocity | In addition to how fast the object travels, also defines the direction in which the object moves |
Acceleration | How quickly an object changes velocity |
Light Speed | 3 x 10 ^8 or 300, 000 km/sec |
First Law of Motion (Inertia) | Is an objects resistance to to changing its motion; how much inertia an object has is determined by the objects mass |
Second Law of Motion | Mass of an object is held constant, the larger the force that applied, the greater the acceleration |
Third Law of Motion | Equal and opposite forces occur when two or more objects interact |
Friction | When two or more objects interact, their irregular surfaces sllide and scrape against one another, impeding the motion of objects. Force that opposes the motion. |
Free Fall | Occurs when an object is pulled down by the gravitational force of the Earth or any other large gravitational body |
Terminal Velocity | The maximum speed that a person or object can achieve while falling toward the Earth |
Pressure | The amount of force that is applied to a specific area. |
Mass | The measurement of an objects inertia, which is dependant on the amount of matter that an object possesses |
Weight | Dependant upon how much mass an object has |
Momentum | A value that describes the amount of inertia and motion an object has |
Impulse | Describes how a change in momuentum occurs. In order to change an objects motion or momentum, a force need to be applied to the object for a period of time. |
Vector | Is a quantity that has magnitude and direction, velocity is a vector |
Rotation | Is to spin about an axis located within the spinning object |
Revolution | Takes place when an object turns about an axis that is located outside the object |
Centripetal Force | "Center Seeking" force causes objects to travel in a circular path |
Centrifugal Force | The sensation that a person feels when traveling in a circular path. "Pulled Out" away from the center. |
Torque | A force that, when applied to An object, causes a turning motion |
Lever_Arm | Distance between the axix of rotation and the point where the force is applied. |
Pulley | A wheel (with an axle or bearing in it's center) on the rim which rides a rope or cord |
Wheel | A circular disk or rim attached to a central rod, called an axle, about which the wheel can turn |
Gears | A by-product of the wheel and axle, can produce huge mechanical advantages in machines. Consist of a circular wheel with teeth carved into them |
Kinetic Energy | Transferred into heat from the friction between air molecules nd the object |
Alternetive Energy | Any form of energy that doesnt orginate from fossil fuels |
Hydroelectric Energy | Generated by sending high speed, high-kinetic energy water through a series of turbines that changes the waters kinetic energy into useable electrical energy |
Heat | The amount of internal kinetic energy of atoms and molecules that flows from a warmer to a cooler environment in an effort to reach equilibrium |
Measured in calories | Heat |
Temperature | Is a scale for measuring thermal energy |
Calorie | The amount of heat needed to increase one gram of water by one degree Celsius or Kelvin |
Fahrenheit | A scale in which the freezing point of water was 32*F and the boiling point was 212*F |
Thermographs | Detect the amount of heat emanating from objects or regions, use colors to determine the temperature |
Thermometers | Measure the heat energy released from an object |
Thermostat | Not only measures the temperature, but also controls heating and cooling systems |
Celsius | Scale based on the freezing point of water (0*C) and boiling point of water (100*C) |
Kelvin | Absolute zero is a theoretical temperature indicating zero heat energy |
States of matter | Solid (ice), Liquid (water), Gas (steam), Plasma (ionized gas) |
Plasma | Occurs when the atoms in a gaseous molecule become ionized, or charged particles |
Convection | Circulating warm, transfers through movement |
Conduction | Acheived through contact with a warm surface; no movement |
Infrared radiation | Exposure to electromagnetic radiation; specifically infrared waves |
Thermodynamics | The field of physics that studies the movement of heat |
Zeroth Law | States that temperature is a method of determining if heat will flow from one object to another. |
First Law of Thermodynamics | Energy can be neither created nor destroyed, but only transformed. One form of energy is changed to another. |
Second Law of Thermodynamics | States that heat will only flow freely from a warm object to a cool environment |
Entropy; also 2nd Law of Thermodynamics | Amount of disorder in a system. The closer it gets to equilibrium it becomes more disordered increasing entropy |
Third Law of Thermodynamics | States that absolute zero, the lowest possible temperature, the point at which there is no energy, can never be reached |
Electrostatic | Study of those electrically charged particles that can be moved from place to place and then held at rest |
Magnets | Consists of tiny, aligned magnetic domains inside materials such as iron |
Magnetic domains | Atoms that have electrons each with a North and South pole spinning the same direction |
Magnetic field | Electrons spinning in the opposite directions |
The key to magnetism is the uniform motion of electrons | |
Electromagnetic waves | Created by the the vibrations of electric charge |
Electromagnet | An iron core wrapped up in electrical, current carrying wire |
Insulators | Inhibit the movement of electricity; non metals |
All forces including electrical forces are measured in Newtons | |
Electrical field | An area where there is an attractive or repulsive electric force between two or more charged particles |
Anode (+) | Always pulls negative charges |
Cathode (-) | Always pulls positive charges |
Electrical current | A flow of positive/negative charges; measured in amps |
Voltage | Potential difference in an object or battery |
Resistance | Slows down the electric charges and in the process causes wires or any of the conductor of electricity to heat up |
Semiconductors | Allow electrical current to trabel without resistance |
Voltage, current, and resistance | Form the basic law of circuits |
Voltage | Current (X) resistance |
Watt | Unit for Power |
Kilowatt | 1,000 watts of power |
Voltage supply | Potential difference in the circuit |
Current flow | Wires are needed to connect the power supply to the resistors and back to the power supply |
Resistance | The flow of electrons can be acheived with wires, electrical devices, and even the power itself |
Electrical current | Closed path through which current travels |
Direct current | Allow electrons to travel only in one direction throughout a circuit |
Alternating current | Vibrates the electrons in the circuit back and forth 60 times a second |
Semi-Conductors | A few free electrons that flow freely in the material such as Germanium and silicone |
Series Circuit | Consist of electrical devices (resistors, capacitors, batteries, switches) arranged in a single line |
Parallel circuit | Allows the electricity to flow through different branches |
Wave | A traveling disturbance that moves energy from one location to another without transferrig matter |
Two major wave classifications | Longitudinal and transvers |
Compression | Medium in longitudinal waves pushes close together at some points |
Rarefaction | Separates from eachother immediately after |
Velocity of wave | Depend upon the material or medium in which it is traveling; typically the denser and more elastic the medium, the faster the wave will travel |
Frequency | How many cycles of vibration occur per second and is measured in cycles per second or Hertz |
Period | Amount of time it takes a wave to vibrate one full cycle |
Wave with a long period has a low frequency, while a wave with a very short period has a high frequency | |
Light, radio, x-rays | Electromagnetic wave |
Electomagnetic wave | Consist of two perpendicular waves, one component of the wave being a vibrating electric field while the other is a corresponding magnet field |
Does not need a medium such as air, water, or steel to travel | Electromagnetic wave |
Radio wave | Wave transmitted is electromagnetic waves. NOT sound waves |
Hz = Hertz | Unit for frequency |
Hertz | represents the number of vibrations or cycles per second of a wave |
KHz | Kilo or 1,000 hertz |
Mhz | Megahertz or one million hertz |
Ghz | Gigahertz or one billion |
Microwave (SHF; super high frquency) | Electromagnetic waves in a frequency range of 3Ghz to 30Ghz |
Created in klystron and magnetron electron tubes | Microwaves |
Damping | Gradual decrease in wave amplitude |
Amplifiers | Typically used to increase the amplitude of the waves before damping reduces the waves to nothing |
Standing waves | Occur when a continuous set of waves reflect off a surface and overlap eachother |
Nodes | Sections that stay still |
Anti-nodes | Sections between nodes that move up and down dramatically |
Resonance | Occurs when the frequency of a continuous wave achieves a standing wave with maximum amplitude |
Transformers | Used to match impedances when mechanical waves encounter new media; provides smoother gradual transition |
Transducer | To change one type of wave into another. i.e. telephones, speakers |
Radar | A frequency band on the electromagnetic spectrum, is an acronym for Radio Detection and Ranging |
Doppler effect | The change in frequency of a wave that results from an objects changing position relative to an observer |
Sound | Travel at 340 m/s or 760 mph |
Human ears | Between 20Hz and 20,000Hz |
Ultrasonic | Those frequencies above the human bardwidth of hearing (20,000Hz) |
Sonar | Acronym for Sound Navigation Ranging is a method of sound waves to determine the distance an object is from a transmitter of sound |
Ultrasound | Systems direct high frequency sound (usually between 5-7Mhz) into particular regions of the body, and measure the time it takes for the sound wave to reflect back to the machine |
Infrasonics (subsonic) | Sounds are those frequencies below the human hearing. Less than 20Hz |
Sound intensity is the energy of the sound wave. For sound and mechanical waves, the energy is determined by the height of its amplitude | |
Pitch of Sound | The combination of frequency and intensity |
Doppler effect | Demonstrates that a waves length decreases as the source moves toward an observer, and increases when the source moves away |
The inverse square law | Sound intensity diminishes according to the inverse square law, which states that the intensity of a sound is inversely proportional to the square of the distance |
Decibal | The loudness of a sound is increased by a factor of ten |
The speed of sound, approximately 331 m/s at 0*C is considered Mach 1 | |
Acoustics | The branch of physics that deals with the science of sound |