Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
8th science 2nd seme
8th grade science 2nd semester exam
| Question | Answer |
|---|---|
| Define motion. | Distance from one object to another is changing. |
| Define reference point. | Place/object used for a comparison to determine if something is moving. |
| Give 3 exemples of reference points. | Tree, sign, building |
| Define and be able to give examples of relative motion | 1. Motion that depends on the reference point 2. cars or airplanes on a runway |
| Be able to compare relative motion from different perspective like skydivers on page 310 | Review page 310 in text book |
| What is the SI unit for distance(length) | Meters(m) or centimeters(cm) |
| What does a centi mean? | one hundredth |
| What does a milli mean? | one thousandth |
| How many centimeters are in a meter stick? | 100 cm |
| Define Speed | Distance traveled per unit of time |
| What is the difference between average speed instantaneous speed? | Average speed, instantaneous Speed -rate in which an object is moving at a given time |
| What is Velocity? | Speed in a given direction;need to know speed and direction |
| What units are used for velocity | SI Unit;meter per second and direction |
| Define vector and give an example | Measurement that includes both magnitude and direction example: Velocity |
| What does slope represent | How fast one variable in relation to the other variable or rate of change |
| How do you calculate slope? | slope = rise/run |
| If the slope of a straight line is constant the the speed of the object is | fast, steady, speed |
| If the slope of a straight line is zero then the speed of the object is | stationary |
| If the slope of a straight line curved, then the speed of the object is | getting faster |
| define acceleration | rate at which velocity changes |
| List 3 ways to accelerate | 1. Increase speed 2. decrease speed 3. changing direction |
| What is deceleration? | An object as it begins to slow down, negative acceleration |
| What are the units for acceleration(of an object moving in a straight line) ? | SI Units=meters per second per second or m/s^2 |
| Be able to explain acceleration . For example what does 8 m/s^2 mean?(see page 322 for text and diagram. ) | Objects speed increases by 8 m/s every second |
| Explain the difference between zero speed and zero acceleration | zero speed - there is no motion zero acceleration - there is no change in velocity |
| Define Force | push or pull |
| What is SI unit for force | Newton (N) |
| Is Force a vector ? | Yes |
| What is net force? | Combination of all forces acting on an object |
| How can you find the net force of two forces acting in the same direction? in opposite direction? | 1.Sum of the two individual forces 2. Difference between two individual forces |
| Can you distinguish between balanced and unbalanced forces? | Balanced-equal forces acting on one object in the opposite direction Unbalanced - causes a change in objects motion |
| UnBalanced forces can cause an object to do what 3 things? | 1. Start moving 2. stop moving 3. Change direction |
| Unbalanced forces on an object always result in what ? | change an objects movement |
| Do balanced forces acting on an object change the objects movement? | No, equal forces are exerted the net force is zero |
| friction is a force caused by what? | Forces that two surfaces exert on each other |
| The strength of friction depends on what two things? | 1. how hard the surfaces push together and 2. types of surfaces involved |
| friction always acts in what direction? | a direction opposite to the direction of the objects motion. |
| list four kinds of friction and give examples of each. | 1 static-sliding a desk 2 sliding- cars brakes 3 rolling- skateboard 4fluid-surfer |
| what factors affect the friction between two surfaces? | 1 how hard they are pushing against each other 2 what type of surface (how smooth) |
| define gravity | force that pulls objects towards each other |
| what are factors affect gravitational attractions | 1 mass 2 distance |
| define law of universal gravitational. | force of gravity acts between all objects in the universe |
| what is mass and what is weight? be able to distinguish between them. | mass-amount of matter in an object weight-measure of gravitational force exerted on an object ex scales |
| what are the units for mass and the units for weight? why aren't they the same? | mass -kilogram mass is not effected by gravitational force weight -pounds |
| be able to explain why your weight on the moon and your weight on the earth are different. | wight less on moon because moon's mass is only a fraction of the earth's |
| according to our scientific definition, what is free fall? | when the only force acting on an object is gravity |
| when are object on earth in free fall? | when an object falls |
| define acceleration due to gravity on earth. | the further an object falls its velocity increases |
| what is the value for acceleration due to the gravity on earth | 9.8 meters per second sqaured |
| How is acceleration due to gravity abbreviated | g |
| what terminal velocity? Can a sky diver have terminal velocity | Force of air resistance equals the weight of an object, yes |
| state Newtons first law of motion | an object at rest will remain at rest and an object moving at constant velocity will remain at a constant velocity unless acted upon by unbalanced force. |
| what are two unbalanced forces on earth that are always unbalanced | gravity and friction |
| what is inertia on what property does inertia depend | tendency of an object to resist a change in momentum. mass |
| why is the first law of motion sometimes called the law of inertia | to stop inertia an unbalanced force must be applied |
| state Newton's 2nd law of motion | acceleration depend on the object mass and on net force acting on the object. |
| what if the formula for force | acceleration equals net force over mass |
| what other units comprise a newton | kg(m/s2) |
| state newtons third law | for every action there is an equal but opposite reaction |
| when given a scenario be able to identify an action force and reaction force | ex. hitting a volleyball |
| Define momentum | quantity of motion of a moving body measured by calculting the bodies mass and velocity |
| What are units for momentum | kilograms and meters per second |
| What does the law of conservation of momentum state? | in the absence of outside forces, the total momentum of objects that interact does not change. |
| Since momentum is conserved, it is never lost but can be | transferred |
| Explain how rockets lift off using Newton's 3rd law. what is the action force? what is the reaction force? | exhaust gases push downward at high velocity rocket's exhaust gases push downwards rocket rises and gases push upwards on rocket. |
| define satellite | object that orbits another object in space |
| what is the SI unit for pressure? | pascal |
| what is a fluid and what causes fluid pressure? | fluid:material that can easily flow;caused by individual partials in a fluid. |
| what is atmospheric pressure and what causes it? | weight of the air pushing down; caused by gravity |
| what happens to atmospheric pressure as elevation increases? as elevation decreases? | decreases increases |
| what is water pressure and what causes it? | water pushing down on you; gravity |
| what happens to water pressure as depth increase? as depth decreases | increases decreases |
| what is buoyant force? | upward force |
| what is buoyancy? | ability to float it acts in the direction opposite to gravity |
| what does archimedes principle state? | buoyant force acting on a submerged object is equal to the weight of the fluid the object displaces |
| use archimedes principle to explain how a ship floats. | it displaces the same amour of fluid equal to the weight of the object |
| Define Density | mass per unit of volume |
| what does paschals principal state | when force is applied to a confined fluid the change in pressure is transferred eqully parts of the fluid |
| what are some examples of paschal's prinicples in everyday life | brakes, barber chair, hydolic life |
| how does a hydraulic system work | multiplies force by applying force to a small area |
| what are some examples of thing that use hydraulics | dump truck, backhoes, screw plows |
| what is the definition of work | exert force on an object causing the object to move |
| what are the units for work | joules |
| what two things does work depend on | force and distance |
| energy makes work easier by | changing the amount of energy, distance and direction |
| the force you apply to the machine is the | input force |
| the force the machine applies to the object | output force |
| the force that you apply over the distance is | input work |
| the force the machine applies over distance | output work |
| in real life output work is | less than input work |
| define energy | ability to work or cause change |
| what the si units for energy | joules |
| KE kinetic energy depends on what two things | mass and velocity |
| which has a greater effect mass or velocity | velocity because its squared doubling velocity will quadruple its kenitic energy |
| PE potential energy) is due to an objects | position and shape |
| gpe (gravitational potential energy) | weight and height |
| GPE depends on two things | an objects weight and height |
| what is the elasticity of PE giving and example | potential associates with objects that can be stressed or compressed, bow strings |
| what does it mean for energy to be transformed | when one energy form is transformed into another energy form. |
| give some examples of energy transformation | toaster oven>eletrical energy to thermal energy |
| strike a match > mechanical to thermal to electro magnetic energy | |
| what is the law of conservation of energy | when one form of energy is transferred to another form of energy no energy is destroyed in the process |
| what does Einstein have to do with law of conservation of energy | he discovered that matter can be transferred to energy therefore in some situations energy is not conserved |
| waves | disturbance that transfers energy from place to place |
| medium | material through which a wave travels |
| chemical wave | waves that require a medium from which to travel |
| vibrations | repeated back and forth or up or down motion |
| transverse wave | waves that wave that move through medium at right angles |
| longitudinal waves | waves that move medium parallel to the way it travels |
| standing wave | wave appear not to move really two waves are pushing through each other |
| wave length | this is between to cooresponding parts of a waves |
| amplitude | max distance the medium carries away the wave from the rest position |
| frequency | number of complete waves past a point in a certain amount of time |
| crest | high part of transfer waves |
| trough | low part of a transfer wave |
| compression | in longitudinal wave they are part of the medium are close together |
| refraction | part of the medium that are spread out |
| node | points of zero amplitude on a standing wave |
| how do you find the amplitude of a transverse wave | measure the distance from the rest to crest of the wave. |
| how do you find the amplitude of a longitude wave | measure how compressed or refracted the medium becomes |
| refraction occurs when a wave strikes a surface and cannot pass through |
Created by:
summerboyi
Popular Science sets