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WMS Science Final 8t
8th grade physical science
Question | Answer |
---|---|
Define parallel circuit | a circuit that has 2 or more separate paths for electrons to follow |
Define mixture | when 2 pure substances are combined so that each substance retains its own properties. |
Where is the strongest magnetic field located? | magnetic poles |
List 4 examples of alternative energy resources? | wind, solar, water, biomass |
What is the law of conservation of matter? | matter cannot be created or destroyed, it can only change forms. |
How are the freezing point and the melting point of a substance related? | the freezing point of a substance is the same as the melting point of the same substance. |
Define chemical property. | a characteristic of matter that allows it to change to something new. |
Where are electrons located in the atom? | in the energy levels of an atom around the nucleus. |
Define inertia | the tendancyof an object ot resist change in motion. |
List & define each type of friction. | static = prevents an object from moving. sliding - slows down an object that slides. rolling = occurs when an object rolls across a surface. |
Define potential energy and give an example. | energy an object has due to its position. ex: stretched rubber band |
Define lever. | a bar that is free to pivotg about a fixed point. |
Define heat. | thermal energy transferred from one object to another because of a difference in temperature. |
List the elecdtromagnetic waves in order, starting with longest wavelength. | Radio - micro - infrared - visible light - ultraviolet - x ray - gamma |
Through which media does sound travel fastest? | solid |
Define transparent and give an example. | objects that allow nearly all the light that strike them to pass through. ex: glass |
Define circuit. | the steady flow of electrons through a conductor. |
List 3 characteristics of nonmetals. | gases at room temp. bad conductors of heat. bad conductors of electricity. |
Why do objects float? | the density of the object is less than the density of the liquid it is in. |
List 3 examples of physical changes | melting, evaporating, solidifying |
What do you need to know to describe velocity? | speed & direction |
Define balanced force | forces that are equal in size but opposite in direction. |
What is Newton's 3rd Law? | for every action, there is an equal but opposite reaction. |
Define inclined plane. | a slanted surface used to raise an object. |
Define wedge. | an inclined plane with one or two sloping sides. |
Define convection and give an example | transfer of thermal energy by the movement of particles. ex: boiling water |
How are sounds produced? | a vibrating object |
Define wave. | Rhythmic disturbance that carries energy, not matter. |
Why are atoms electrically neutral? | There are equal numbers of protons & electrons. |
How do magnets attract one another? | opposites attract: north pole of one magnet attracts the south pole of another. |
What kind of energy does a burning fire produce? | radiant & thermal |
List 3 characteristics of metals. | solides at room temp (except mercury), good conductors of heat & electricity, malleable & ductile. |
Where is the mass of an atom found? | in the nucleus; the protons & neutrons |
List the 4 states of matter and explain how the particle move in each. | solid = vibrate in place, liquid = slide past one another, gas = fly all over, plasma = move too fast to observe |
What is the equation for speed? | speed = distance/time |
What is Newton's 1st Law? | Object remains at rest or in motion unless a net force acts on it. |
What does a circuit breaker do? | a device designed to open an overloaded circuit and prevent overheating. |
List 3 ways work is done. | pushing something, pulling something, lifting something |
Define series circuit. | a path created for a current that allows only one route for the current. |
What is a simple machine? List all types. | A device that does work with only one movement and changes the size or direction of a force. (lever, wedge, pulley, screw, wheel&axel, inclined plane) |
Define electric current | the flow of electric charge |
What is power? | the rate at which work is done |
Define loudness. | the human perception of the energy a wave carries. |
List 3 examples of heterogeneous mixtures | vegetable soup, italian salad dressing, chocolate chip cookie |
Define mechanical advantage | the amount by which a machine multiplies an imput force. |
List 3 examples of physical properties | shape, size, density |
Define compound machine. | when 2 or more simple machines work together. |
How do you calculate density? | density = mass/volume |
Define radiation and give an example. | transfer of energy by electromagnetic waves. ex: infrared lamps at restaurants |
List 3 examples of chemical properties. | ability to burn, ability to react with oxygen, toxicity |
Define air resistance. | upward force acting on an object falling through the air. |
Define static charge | the buildup of electric charges on an object |
Define matter | anything that has mass & takes up space. |
List 3 examples of chemical changes. | burning paper, digestion of hamburger, iron rusting |
On a speed-time graph, what does a horizontal line show? | show the change in speed is zero |
Define momentum | a measure of how hard it is to stop an object. |
What is Newton's 2nd Law? | Force = mass x acceleration |
What happens to materials when they get hot? | they expand |
Define rarefaction | a place where molecules are far apart |
Define reflection | when light bounces off a surface. |
What is the speed of an EM wave? | 300,000 km/s |
Define wave frequency. | the number of waves that pass a certain point in one second. |
Define medium | the material in which a wave travels. |
Why do objects appear red? | they absorb all colors but red, which is reflected. |
Define refraction. | when waves change speed when they pass from one medium into another. |