7th grade physical science-energy

8/9/2019 7th Grade Physical Science-Energy

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A construction worker uses a boardand log as a lever to lift a heavyrock. If the input length(eort) is 3meters and the output length(resistance) is 0.! meters" what isthe ideal mechanical advantage of

the lever# I$A% d&' d% 3m'0.!m%

*+,A- /escribe how ener work


2/20

ys ca

Science

Energy &

Power


3/20

The Nature of Energy Energy the ability to do work or cause a

change. work is the transfer of energy SI unit for energy is Joules the same as Work

Two main types of energy: Kinetic and

Potential Kinetic Energy: the energy of motion Potential Energy: Energy stored for use at a later

time


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Calculating KineticEnergy Kinetic Energy: the energy of motion The amount of kinetic energy depends on the objects mass

and velocity nergy is transferred during work

The more work one does on an object

The more energy one imparts on the object

Kinetic energy !ass " #elocity$

$

%hen mass is doubled& Kinetic Energy is doubled

%hen velocity is doubled& Kinetic Energy is

'uadru(led))
https://www.brainpop.com/science/energy/kineticenergy/https://www.brainpop.com/science/energy/kineticenergy/https://www.brainpop.com/science/energy/kineticenergy/


5/20

Whats the KineticEnergy?

%hat is the Kinetic Energy *in +oules, of anob-ect with a mass of / kg and a velocity of /m0s1

%hen mass is doubled& Kinetic Energy isdoubled

%hen velocity is doubled& Kinetic Energy is'uadru(led))


6/20

/o 1ow2 A car is moving with the velocity of 0 m'sand is having mass of 4!0 5g. 6alculate its 5ineticenergy#

$ass of the body m % 4!0 5g" 7elocity v % 0

m's"

5inetic energy is given by 5.& % 4 mv4% 4 8 4!05g (0 m's)4 % 4!00 9oules

5& % 4!0 kg : 04% 4!000'4 %4!009

5&% $74' 4% 9oules

*+,A- /escribe how energy" workand ower are related name and


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Potential Energy: nergystored for use at a later time

! Types: lastic "otential nergy:

nergy stored in springs# bow and arrow# stretched elasticor rubber bands$

%ssociated w& objects that can be stretched or compressed$

'ra(itational "otential nergy: 2eight and weight de(endant *notice its weight3 N4T

mass), 5PE work done to lift and ob-ect to a height 5PE %eight " 2eight )remember that weight * mass + ,$-

m&s!. 5PE mass " 6.7 m0s$ " 2eight

GPE = 100 N x 300 m = 30000 Nm =30000 !o"les
https://www.brainpop.com/science/energy/potentialenergy/https://www.brainpop.com/science/energy/potentialenergy/


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8i9erent orms ofEnergy ; di9erent ty(es2

!echanical Thermal Energy Chemical Energy

Electrical Energy Electromagnetic Energy Nuclear Energy


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!echanical Energy %ssociated w& the motion )kinetic. or position of an object

)potential. Kinetic Energy exists whene#er an o$%ect which has

mass is in motion with some #elocity E#erything yo"see mo#ing a$o"t has 'inetic energy

Potential Energy exists whene#er an o$%ect which has

mass has a (osition within a )orce *el+ ,he moste#ery+ay exam(le o) this is the (osition o) o$%ects inthe earth-s gra#itational *el+

5PE %eight

"2eight


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Thermal Energy

%ssociated w& the total energy of the particles)atoms and molecules. in an object$ %s thermalenergy increases# the particles increase in speedand the thermal energy )temperature. of theobject increases$


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Chemical Energy

the energy stored in chemical bonds$The potential energy stored incompounds$


12/20

Electrical Energy /o(ing electrical charges$ lectricity

00
https://www.brainpop.com/science/energy/electricity/https://www.brainpop.com/science/energy/electricity/


13/20

/o 1ow2 9ohn picked up a bowlingball that was 0 kgs" he lifted it upto his chest which was .! meter

from the ground and he threw itdown the alley at ;m's what is the5inetic energy# +hat was the

potential energy#

*+,A- *tate the law of

conservation of energy


14/20

Electromagneticenergy Tra(els in wa(es# associated w& light# infrared# ultra(iolet#

microwa(es# +1rays# etc 2onger wa(elength yields low fre3uency 4 low energy Shorter wa(elength yield high fre3uency 4 high energy
https://www.brainpop.com/science/energy/electromagneticspectrum/https://www.brainpop.com/science/energy/electromagneticspectrum/


15/20

Nuclear Energy %ssociated w& the fusion or 5ssion of nuclear

atoms$

-he fusion ofhydrogen intohelium fuels

the power ofthe sun
https://www.brainpop.com/science/energy/nuclearenergy/https://www.brainpop.com/science/energy/nuclearenergy/


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Energy Conversion andConservation /ost forms of energy can be converted from one ty(e

to another.


17/20

nergyConversio

n


18/20

Power "ower: the rate at which work is done

"ower * work & time and since: Work * force + distance$

"ower * 7orce + 8istance

Time SI 9nit for "ower is the Watt Watt * Joule & Second ;orsepower : %n %merican unit of power

The amount of work a horse does when it lifts


19/20

Power

Pro$lems

+ % > : /? % > : / ' - ? % 3! 1 : 0 m ' ! sec ? % 3!0 9 ' !

sec % 0 9'sec ? % 0 +atts

W = P x , con#ert 1 ho"r into secon+s. 1ho"r /0 min x /0 sec

1 hr 1 min

Wor' = /0 watts x 3/00 sec =1/000 !o"les = 1/ Kilo%o"les

SWBAT- Create an incline plane using a computer program that will allow to calculate kinetic and

potential energy. And they will use a worksheet to collect data from the simulation and use it to

better understand the factors that contribute to an objects potential and kinetic energy.


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/ue $onday the 4thread ; !0answer all of and [email protected] pg.!;3 and answer " 4 and 3 on pg.;3

&nergy *kate ?ark 6alculatingkinetic and

http2''phet.colorado.edu'en'contribut

ions'view'3B
http://phet.colorado.edu/en/contributions/view/3749http://phet.colorado.edu/en/contributions/view/3749http://phet.colorado.edu/en/contributions/view/3749http://phet.colorado.edu/en/contributions/view/3749http://phet.colorado.edu/en/contributions/view/3749http://phet.colorado.edu/en/contributions/view/3749

7th grade physical science-energy

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