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Published byEllen Willis Modified over 9 years ago
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Speed = distance/time Velocity = displacement (distance with a direction)/time Acceleration = change in velocity/time *Acceleration occurs when you speed up, slow down, or change direction.
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Newton’s 1 st law – An object at rest will remain at rest and an object in motion will remain in motion unless acted on by an outside force. Example: You are standing in a moving bus. The bus stops. You continue to move forward. Newton’s 2 nd law- Force = mass x acceleration Example: If you push a big car and a little car with the same amount of force, the little car will accelerate more Newton’s 3 rd law – for every force in nature, there is an equal and opposite force Example: You step forward out of a boat, the boat moves backward in the water
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Weight is an example of force Weight = Mass x gravitational acceleration (9.8 m/s 2 ) Gravitational Acceleration – rate at which gravity pulls an object toward it. On the earth, all objects fall at a rate of 9.8 m/s 2. Since the moon is so much smaller, acceleration due to gravity on the moon is 1.6 m/s 2 Gravity is dependent on the mass of objects and the distance between those objects
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Mass is the amount of matter in an object and does not change Weight is mass multiplied by gravity, weight can change Example: A person has the same mass on the earth and the moon, but their weight is less on the moon
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Work = force x distance two conditions must be met for work to occur › the object must move through a distance › a force must act upon the object in the direction the object moves
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Do not change the amount of work, but change the direction or the distance of the force
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6 types of simple machines 1. Pulley - uses grooved wheels and a rope to raise, lower or move a load. 2. Lever - A lever is a stiff bar that rests on a support called a fulcrum which lifts or moves loads. 3. Wedge - an object with at least one slanting side ending in a sharp edge, which cuts material apart. 4. Wheel and axle - A wheel with a rod, called an axle, through its center lifts or moves loads. 5. Inclined plane - is a slanting surface connecting a lower level to a higher level. 6. Screw - is an incline plane wrapped around a cylinder
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When trading effort for distance, we gain the advantage of multiplying our effort force using what is called a mechanical advantage. The mechanical advantage is the ratio of the resistance force to the effort force and may be calculated using either force or distance:
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A rhythmic disturbance that transfers energy through matter and space; exists only as long as it has energy to carry. Speed of a wave = wavelength x frequency
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Compressional waves Examples: sound and seismic
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– energy travels at a right angle to the medium, doesn’t have to have a medium Example: light or electromagnetic waves, waves on a string, water waves
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Frequency increases from radio to gamma, wavelength decreases from radio to gamma Radio waves have the longest wavelength, lowest frequency, and the least amount of energy In visible light, the color red has the longest wavelength, lowest frequency, and the least amount of energy In visible light, the color violet has the shortest wavelength, highest frequency, and most amount of energy Gamma waves have the shortest wavelength, highest frequency, and most amount of energy
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Radio – radio, TV, and cell phone signals Microwave – microwave oven Infrared – heat (cameras that can sense different amounts of heat from objects) Visible – what we see, colors Ultraviolet – sunlight or tanning bed X-ray – used by doctors to see your bones and teeth Gamma – nuclear radiation
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Reflection – wave hits a different medium a bounces back Example: aluminum foil reflecting sunlight Refraction – wave slowing down or speeding up when it hits a different medium Example: light slows down in water, so a pencil appear broken when part is in the water and part is not Interference – occurs when two waves meet Example: Standing wave is when two waves add together Diffraction – bending of a wave around an object Example: Colors that you see when looking at a cd are caused by light being bent
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Build up of charges on an object
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Friction – rubbing Example: Rubbing a balloon on your hair makes it stick to the wall or rubbing your feet on the floor to shock someone Induction – transferring charge by passing a charged object close to another object Example: taking that same balloon you rubbed on your hair and moving it near small pieces of paper, the paper will become charged and stick to the balloon. Conduction – transferring charge by direct contact Example: electrons moving from a battery through a wire
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Flow of electrons from negative to positive Two types of current: – Alternating Current – current flows in forward and reverse directions Example: Electricity in your home – Direct current – current only flows in one direction Example: Battery Formula for Current is Ohm’s law: Current (I) = Voltage (V) / Resistance (R)
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Series Circuit – only has one pathway through which the current can flow Parallel Circuit – has multiple pathways through which the current can flow
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Magnetism Is due to charges (domains) inside of a material all lining up in the same direction, so one side of the object is negative and one side is positive. These domains can be unaligned by jarring or heating a magnet. Electromagnets are created by placing a metal object inside a coil of wire and moving electric current through the wire. This causes the metal to become magnetic. You can increase the magnetism by increase the coils, increasing the voltage, or increases the number of coils. Generators (mechanical energy to electrical energy): when you spin a coil of wire inside two magnetic poles it produces an electric current.
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