Shared Flashcard Set

Details

9th grade
exam
65
Science
9th Grade
05/23/2011

Additional Science Flashcards

 


 

Cards

Term
Why does placing wheels under a heavy box reduce the necessary force require to push it along at a constant speed?
Definition
The wheels allow the load to be equally distributed and moves the force on movement onto something that rolls reducing the required force
Term
identify the 4 fundamental forces in natture
Definition
Strong Nuclear Power
Weak NP
Elcromagnetic
Gravity
Term
What happens whenever a net force acts on an object?
Definition
All of the forces form together
Term
Identify the type of enregy stored in a stretched bungee cord.
Definition
Potential
Term
explaon how the sunlight converted into potential energ by plants
Definition
They absorb it
Term
Explain how the kinetic energy of am object changes when the speed of the object doubles
Definition
it increases
Term
Contrast chemical energy with mechanical energy.
Definition
chemical energy is when the energy that is released when a chemical compound reacts to produce new compounds. A mechanical energy is the sum of the kinetic and potential energy of large-scale objects in a system.
Term
Explain why free-fall acceleration can be regarded as constant for objects falling within a few hundered miles of Earth's Surface.
Definition
Since the radius of Earth is far greater(rough: 6400km) than a few 100m, you can neglect that distance and still have g=9.80
Term
Apply Newtonn's third law of motion to explain how 2 billiard balls, moving toward each other at the same speed, collide and move away from each other at the same speed as before.
Definition
The action of them hitting each other is = by them bouncing. They would move in the opposite direction.
Term
apply the concept of momentum to compare the mass and velocity of a slowmoving train and a hih-speed bullet
Definition
The train has a larger mass
Term
Infer what you can say about the velocity of a car that is moving with a constant momentum.?
Definition
the car is moving at constant velocity.
Term
Apply Newtpn's first and secong laws to explain why an object moving in a circular path at a constant speed is undergoing acceleration and has a force exerted on it.
Definition
When the object is moving in a circular path, applying Newton's first law of motion, there is no outside or unbalanced force exerted upon the object, so it stays in constant motion. The force that is being exerted upon it is balanced and so it the mass times acceleration is the same as the force, so it stays in constant acceleration and at a constant speed as it goes on the same circular path.
Term
Explain why a bacward-facing car seat is safer for an infant than a forward-facing car seat during a collision or abrupt stop.
Definition
The baby would not slide forard, the cack af the seat safely distributes the force pushing him fwd.
Term
Use the concept of inertia to illustrate why volleyball is not played with a ball that hass mass similar to a bowling ball?
Definition
The Action Force of the ball would be greater than the reaction force of your hands trying to hit it. This could cause you to break a finger...
Term
explain the relationship between work and power
Definition
Power is the rate of doing work
Term
Can you Explain how machines make work easier if they still require that same amount of work be done?
Definition
Machines make work easier by allowing you to use less force over a greater distance to get a task accomplished
Term
List two ways mechanical energy can be transfomed to nonmechanical energy
Definition
•Moving an object across another can result in heat through friction. This is conversion of the mechanical energy into thermal energy.
•In an electric motor, the (mechanical) rotation of the coils results in electrical current and therefore electrical energy.
Term
Describe why a high-efficiency machine is more desirable thana low-efficiency machine?
Definition
"High efficiency" means that a large percentage of the energy used by the machine is converted into the desired output.
Term
"High efficiency" means that a large percentage of the energy used by the machine is converted into the desired output.

Read more: http://wiki.answers.com/Q/Describe_why_a_high-efficiency_machine_is_more_desirable_thana_low-efficiency_machine#ixzz1NDX8ifVR
Definition
Because energy is lost due to air resistance and through inelastic deformation of the ball with the ground when it bounces.



Read more: http://wiki.answers.com/Q/Explain_why_the_height_of_a_bouncing_ball_decreases_after_each_bounce#ixzz1NDXNSwtx
Term
How does a skier gliding down a hill illustrate the conservation of energy
Definition
When a skier goes down a hill, the skier slowly loses potential energy the farther down the hill he is. This causes the skier's kinetic energy to increase, as predicted by the law of conservation of energy
Term
Why does a ceramic bowl keep oatmeal hot longer than a stainless steel bowl
Definition
A ceramic bowl will keep oatmeal hot longer than a stainless steel bowl because the stainless steel conducts heat much better and the ceramic bowl if heated will hold its heat much longer than stainless steal
Term
Explain which method of heat transfer can take place if 2 objects at different temp. are placed w/o touching each other in a vacuum
Definition
radiation.
Term
Explain why steam (gas) has a lower specific heat than water (liquid).?
Definition
molecular density of the gas is less than the liquid
Term
Describe the method of heat transfer involved when you mix hot water with cold water to make lukewarm water.
Definition
conduction
Term
Determine which is the best type of skillet. Some people prefer a heavy cast iron skillet while others prefer a thin stainless steel one
Definition
Describe the method of heat transfer involved when you mix hot water with cold water to make lukewarm water

Read more: http://wiki.
Term
Which of the 4 common types of nuclear radiation can be described as an uncharged particle.
Definition
neutron
Term
Why are gamma rays more dangerous than alpha paticles or beta
Definition
Gamma rays can pass through many more materials, such as clothing or walls. tjan alpha or beta particles can.
Term
describes what happens to the mass number and the atomic number of an atom during beta decay.
Definition
During beta decay, a neutron in the nucleus decays to form a proton and an electron. Atomic # changes bc there is one more proton in the nucleus. Mass # does not chance bc the total number of protons and neutrons in the nucleus does not change.
Term
Tell the process to describe how nuclear fission is used to produce electricity.
Definition
* Uranium-235 nuclei undergo a chain reaction.
* A collan absorbs energy from the chain reaction.
* Water absorbs energy from the coolant and changes tp steam.

* The steam turns a turbine attached to a generator.

* A generator changes the mechanical energy of the spinning turbine in2 electrical energy.
Term
List 3 activities that add to an individual;s exposure to radiation.
Definition
smoking, traveling in plane, and x-ray
Term
How do smoke detectours use nuclear radiation to detect a fire.
Definition
A radioactive element in the smoke detector . The alpha particles produce elecric curren when smoke itterrups the current
Term
What two factors determine the risk of damage from nuclear radiations?
Definition
type of radiation and the amt. of radiation exposure.
Term
Why is it important to use low levels of nuclear radiation for detection of diseases?
Definition
Low doses of radiation can have beneficial uses, but high lvls of nuclear radiation can cause radiation sickness.
Term
What are 2 ways to reduce the lvls of radon gas in a building?
Definition
Install vent tah draw air out of a building.
Seal cracks in the foundation of a building.
Term
What are two advantages and two disadvantages of using nuclear fission to generate electricity
Definition
Adv: Nuclear power does not produce gases that pollute the air; there is more energu in known uranium reserves than in known oil or gas reserves.
Dis.: Radioactive products of fission can release nuclear radiation into the environment; nuclear power plants are expensive to build.
Term
list two living elements and two non living elements in the ecosystem of an ocean reef
Definition
Two living elements of the reef are plankton and and algae. Two nonliving elements are rocks and sand.
Term
explain how the word "interrelatedness" is a key to understanding the stability
Definition
Humankind benefits from a multitude of resources and processes that are supplied by natural ecosystems. Collectively, these benefits are known as ecosystem services and include products like clean drinking water and processes such as the decomposition of wastes.
Term
List two human activities that cause changes in ecosystems
Definition
Clearing trees, and driving cars.
Term
Can you discuss the importance of an informed public, in that all all citizens have a better understanding of how ecosystems work before they vote on the construction of dams, highways,malls,housing development,etc?
Definition
Ecosystems have no particular size. An ecosystem can be as large as a desert or a lake or as small as a tree or a puddle. If you have a terrarium, that is an artificial ecosystem. The water, water temperature, plants, animals, air, light and soil all work together.
Term
Name the energy transfer process plants use to convert the sun's energy into stored chemical energy,
Definition
photosynthesis
Term
state where all fossil fuels come from, and give an example of the three phases.
Definition
They come from organic compounds.
Liquid:oil
Solid: Coal
Gas: natural gas
Term
state a disadvantage of the use of nuclear power
Definition
It would cost a lot to clean if a spillage occured.
Term
State the 2 proccesses by which we obtain energy from the nucleus of an atom.
Definition
fission; fusion
Term
What is used in present-dau nuclear power plants?
Definition
fission
Term
How can reusing rinse water from dishes and laundry can reduce the use of energy and cut down pollution?
In: Pollution [Edit categories]
Definition
by reusing them you will be recycleing the water, and so you would be using less water
Term
describe how the human activity of driving a car contributes to global warming
Definition
it puts out pollution in the air and uses gas. requires the combustion of tremendous amounts of fossil fuels.
Term
list three major contributors to water pollution
Definition
human activities, fertilizers, and pesticides, differeny materials that are water pollutants
Term
Describe the harmful effects of acid rain on streams and lakes and on soil.
Definition
Makes water acidic and causes organisms to die.
Make soil less fertile
Term
Explain why contaminants in soil are hard to remove?
Definition
because the are usually chemicals such a s oul and gasoline.
Term
Define temp in terms of KE
Definition
temp. is the measure of KE
Term
Explain how a liquid thermometer measures temp.
Definition
liquid collapses and expands
Term
Why cant an objext never reach a temp of absolute 0
Definition
there is always motion
Term
Why is a fan blade spinning at a constant speed constantly accelerating.
Definition
it changes direction
Term
How is a frame reference used to describe motion?
Definition
Its a system 4 specifying the precise location of objects in space and time.
Term
What is the differece b/ K friction and static friction?
Definition
Static friction resists sliding motion,
Term
What happens to an object when an unbalaced force acts on it
Definition
it moves
Term
a nonrenewavke energy resource formed from the remains of organisms that lived long ago; exanles include oil, coal, and natural gas.
Definition
fossil fuel
Term
the energy produced by heat within the Earth
Definition
geothermal energy
Term
a resource that forms at a rate that is much slower than the rate at which the resource is consumed
Definition
nonrenewable resource
Term
a natural resource that can be replaced at the same rate at whic the resource was cosumed
Definition
renewable resource
Term
a gradual increase in avg. global temp.
Definition
global warming
Term
an undesirable change i the natural environment that is caused by the into of substances that are harmful to living organisms or by excessive wastes, heat, noise, or radiation.
Definition
pollution
Term
a kind of energy created by the physical movement or rotation, revolution etc of anything.Since most of the movements done and energy created are done by machines,
Definition
mechanical energy
Term
The energy of a particle or system of particles derived from position, or condition, rather than motion. A raised weight, coiled spring, or charged battery has
Definition
potential energy
Term
The energy possessed by a body because of its motion, equal to one half the mass of the body times the square of its speed.
Definition
kinetic enrgy
Supporting users have an ad free experience!