REPÚBLICA BOLIVARIANA DE VENEZUELA MINISTERIO DEL PODER POPULAR PARA LA DEFENSA UNIVERSIDAD NACIONAL EXPERIMENTAL POLITÉCNICA DE LA FUERZA ARMADA U.N.E.F.A. Núcleo, Maraca.
Prac$'ca / Calor D'la$ac'(
Pro!e"or#
E"$%&'a($e"#
)o"* +-e
L%'" P*re CI# //0112/1 )e!er"o( Col'(a CI# /3453146 Secc'(# IN+ELE2SD4/ Maraca /27407/483
Objetivos del experimento
Calor Específico de las Sustancias Objetivo General: &e$er-'(ar el calor e"9ec'!'co &e %(a "%"$a(c'a a $ra:*" &e la
relac'( Ce ; <7 =->?T@ Objetivo Específico:
8. De$er-'(ar -e&'a($e e("ao e( el laora$or'o el calor e"9ec!'co &e %( l%'&o. /. Calc%lar -e&'a($e e("ao e( el laora$or'o el calor e"9ec!'co &e %( "l'&o. Equivalente Eléctrico del Calor Objetivo General# De$er-'(ar el e%':ale($e el*c$r'co &el calor.
Objetivo Específico:
8. De$er-'(ar e9er'-e($al-e($e el e%':ale($e el*c$r'co &el calor. /. De!'('r e9er'-e($al-e($e %(a %('&a& &e ca($'&a& &e calor e( relac'( co( %(a "%"$a(c'a 9a$r(. Dilatación érmica Objetivo General# O"er:ar el e!ec$o %e 9ro&%ce( lo" ca-'o" &e $e-9era$%ra
e( la" "%"$a(c'a". Objetivo Específico:
8. O"er:ar el e!ec$o &el calor "ore %(a l-'(a e( !or-a e9er'-e($al. /. O"er:ar %e el e!ec$o &el calor "ore -e$ale" &'!ere($e", (o e(era el -'"-o e!ec$o &e &'la$ac'(. 2. De$er-'(ar e9er'-e($al-e($e la &'la$ac'( c%'ca &e %(a "%"$a(c'a l'%'&a "l'&a.
!spectos teóricos
E"$a Se%(&a e9er'e(c'a !"'ca e"$%&'are-o" lo %e e" el calor la &'la$ac'( &e la" "%"$a(c'a" o -a$er'ale". La $o-a &e &a$o" o"er:ac'( &e$alla&a &e ca&a 9a"o, 9er-'$e( &e %(a -a(era 9rc$'ca e($e(&er el !e(-e(o a e"$%&'ar. U( c%er9o o "%"$a(c'a 9%e&e :ar'ar "% co($e$%ra o "% e"$a&o (a$%ral e( el a-'e($e, 9or -o$':o &e la :ar'ac'( e( "% $e-9era$%ra (a$%ral, e( *l "e o"er:ara( lo" ca-'o" rac'a" al a%-e($o o &'"-'(%c'( &e lo" ra&o" calor!'co" &e &'cGo e"$a&o (a$%ral &el -a$er'al, el calor &'la$ac'( %e "e le e(era o "e le "ea "%-'('"$ra&o a la "%"$a(c'a 9ro:ocara e( ella %(a reacc'( -% (o$or'a &e9e(&'e(&o a "ea &el -a$er'al o &e la "%"$a(c'a %e e"$e e( %"o, e" &ec'r e( al%(o" ca"o" el -a$er'al ca-'ara "% $e$%ra, e( o$ro" "% e"$a&o, 9ero a-o" "er( ca-'o" -% e:'&e($e" 9ara (%e"$ra" o"er:ac'o(e". Calor: el calor &e %( c%er9o (o e" -" %e %( ca-'o o :ar'ac'( e( "%
$e-9era$%ra (a$%ral la c%al :'e(e e9re"a&a e( ra&o" ce($ra&o", ca&a "%"$a(c'a &e9e(&'e(&o &el a-'e($e e( %e "e e(c%e($re 9o"ee %(a $e-9era$%ra '('c'al &e ac%er&o al "'$'o &o(&e e"$* %'ca&o, e" &ec'r ca&a %(o &e9e(&er &el a-'e($e e( el c%al e"$e &e"e(:%el$o. Dilatación: la &'la$ac'( :a &e la -a(o co( lo" ca-'o" calr'co" &e lo" c%er9o",
al "o-e$er %( c%er9o a %(a $e-9era$%ra -%cGo -" a"ce(&e($e &e lo (or-al &e9e(&'e(&o &el -a$er'al o "%"$a(c'a "er( o"er:a&o" ca-'o" e( ello" -% e:'&e($e" e( "% $e$%ra, "% lo('$%&, "% :ol%-e( e($re o$ra".
Co-o ca&a -a$er'al 9o"ee %( coe!'c'e($e &e $e-9era$%ra &'"$'($o, e" &ec'r (o $o&o" 9or -e&'o &el calor reacc'o(a( &e la -'"-a -a(era, o ca-'a a la -'"-a $e-9era$%ra. Lo" coe!'c'e($e" &e &'la$ac'( "o( lo" ca-'o" crec'e($e" &e lo('$%& %e e9er'-e($a la %('&a& &e la lo('$%& al a%-e($ar "% $e-9era$%ra e( %( ra&o e"9ec!'co. El dilatómetro: e" %( '("$r%-e($o &e -e&'c'( e(cara&o e( e(erar calor 9ara
9ro&%c'r %( -a$er'al &e$er-'(a&o ca-'o" e( "%" coe!'c'e($e" &e &'la$ac'(.
Efectos de la dilatación térmica del metal
!plicaciones de la dilatación térmica:
La
&'la$ac'(
a9ro:ecGar"e.
$*r-'ca El
al%-'('o,
9%e&e 9or
&'la$a &o" :ece" -" %e el G'erro. S' "ol&a-o"
eHe-9lo, e(
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arra &o" $'ra" 9aralela" &e e"$o" -e$ale" la cale($a-o", la -aor &'la$ac'( &el al%-'('o
Gar %e la arra "e
&ole Gac'a %( la&o "' la e(!r'a-o" oc%rr'r eac$a-e($e al co($rar'o. Jare-o" !ar'ca&o a" %( $er--e$ro %e 9%e&e "eKalar(o" la" $e-9era$%ra" , e( c'er$o" ca"o", %( $er-o"$a$o, co-o -%e"$ra la 'l%"$rac'(. Dilatación térmica: la &'la$ac'( $*r-'ca corre"9o(&e al e!ec$o e( el c%al, la"
"%"$a(c'a" "e ara(&a( al a%-e($ar la $e-9era$%ra. E( oHe$o" "l'&o", la &'la$ac'( $*r-'ca 9ro&%ce %( ca-'o e( la" &'-e("'o(e" l'(eale" &e %( c%er9o, -'e($ra" %e e( el ca"o &e l%'&o" a"e", %e (o $'e(e( !or-a 9er-a(e($e, la &'la$ac'( $*r-'ca "e -a('!'e"$a e( %( ca-'o e( "% :ol%-e(.
Dilatación lineal: Co("'&ere-o" 9r'-ero la &'la$ac'( $*r-'ca &e %( oHe$o "l'&o,
c%a" &'-e("'o(e" l'(eale" "e 9%e&e( re9re"e($ar 9or l 4, %e "e &'la$a e( %(a ca($'&a& ?L. E9er'-e($al-e($e "e Ga e(co($ra&o %e 9ara ca"' $o&a" la" "%"$a(c'a" &e($ro &e lo" l-'$e" &e :ar'ac'( (or-ale" &e la $e-9era$%ra, la &'la$ac'( l'(eal ?L e" &'rec$a-e($e 9ro9orc'o(al al $a-aKo '('c'al l 4 al ca-'o e( la $e-9era$%ra ?$, e" &ec'r# ; Do(&e
;
.
"e lla-a coe!'c'e($e &e &'la$ac'( l'(eal, c%a %('&a& e" el rec9roco
&el ra&o, e" &ec'r C 8. Dilatación superficial: e" el -'"-o co(ce9$o %e el &e &'la$ac'( l'(eal "al:o %e
"e a9l'ca a c%er9o" a lo" %e e" ace9$ale 9re!er'le co("'&erarlo" co-o re'o(e" 9la(a" 9or eHe-9lo, %(a 9la(cGa -e$l'ca. Al "erle $ra("-'$'&a c'er$a ca($'&a& &e calor la "%9er!'c'e &el oHe$o "%!r'r %( '(cre-e($o &e rea# ?A.
;
;
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Do(&e Q "e lla-a coe!'c'e($e &e &'la$ac'( "%9er!'c'al. Dilatación volumétrica: la &'la$ac'( :ol%-*$r'ca &e %( l%'&o o %( a" "e
o"er:a co-o %( ca-'o &e :ol%-e( ?V e( %(a ca($'&a& &e "%"$a(c'a &e :ol%-e( V4, relac'o(a&o co( %( ca-'o &e $e-9era$%ra ?$. E( e"$e ca"o, la :ar'ac'( &e :ol%-e( ?V e" &'rec$a-e($e 9ro9orc'o(al al :ol%-e( '('c'al V 4 al ca-'o &e $e-9era$%ra ?$, 9ara la -aor 9ar$e &e la" "%"$a(c'a" &e($ro &e lo" l-'$e" &e :ar'ac'( (or-al-e($e acce"'le" &e la $e-9era$%ra, e" &ec'r# ;
;
.
Do(&e "e lla-a coe!'c'e($e &e &'la$ac'( :ol%-*$r'ca, -e&'&a e( la -'"-a %('&a& %e el coe!'c'e($e &e &'la$ac'( l'(eal / al!a. Se 9%e&e &e-o"$rar !c'l-e($e %"a(&o el lera %e# ; 2 A(loa-e($e "e 9%e&e o$e(er el coe!'c'e($e &e &'la$ac'( "%9er!'c'al Q &a&o 9or# ; / a %e Ge-o" e9l'ca&o &e!'(o" lo" co(ce9$o" a"'co" &e lo %e "e $ra$a el calor la &'la$ac'o( a co($'(%ac'o( :ere-o" la 9ar$e e9er'-e($al ecGo" e( el laora$or'o &e cla"e. "re#untas $% &'a temperatura es un concepto microscópico o macroscópico(
E" -'cro"c9'co, e"$a la 9o&e-o" o"er:ar a $ra:*" &e la" 9ar$c%la" %e co(!or-a( %( "'"$e-a, e" &ec'r, e"$ 9re"e($e e( lo" c%er9o". )% &"or qué los la#os se con#elan desde la superficie(
Por%e "e co(ela( H%"$a-e($e c%a(&o la $e-9era$%ra &e a-'e($e e" -%cGo -e(or a la &el lao -'"-o. E" &ec'r, (o "e co(ela( "olo", $'e(e %e :er co( la $e-9era$%ra &e "% e($or(o. O:'a-e($e, la 9ar$e %e e"$ e( co($ac$o &'rec$o co( el e$er'or, e" la 9r'-era e( "er 9e(e$ra&a 9or el !ro, 9or e(&e, "e co(ela( &e"&e la "%9er!'c'e Gac'a el !o(&o, 9ero e" %( 9roce"o 9a%la$'(o, (o oc%rre $o&o &e ol9e. Ta-'*( "' "e &err'$'e"e el G'elo, la 9ar$e &e la "%9er!'c'e "era la 9r'-era e( &e"co(elar"e, 9%e" el !o(&o, al llearle -e(o" calor, $ar&a -" e( &erre$'r"e. El a%a $'e(&e a co("er:ar la" $e-9era$%ra", 9or e"o "% $e-9era$%ra (o ca-'a al -'"-o $'e-9o %e la $e-9era$%ra &e a-'e($e.
*% &"uede usted explicar por qué la columna de mercurio primero desciende + después sube cuando se expone un termómetro de mercurio al calor(
La col%-(a &e -erc%r'o "%e c%a(&o "e e9o(e al calor &e'&o al a%-e($o &e $e-9era$%ra, e"$o "e &ee a %e la :ar'ac'( &e $e-9era$%ra a!ec$a el :ol%-e( &el l%'&o &e -a(era %e el -'"-o "e &e"9laa 9or el &e9"'$o %e e"$a ra&%a&o. ,% &Enumere por lo menos - aplicaciones en la que interviene la dilatación térmica(
La &'la$ac'( $*r-'ca 9%e&e a9ro:ecGar"e. El al%-'('o, 9or eHe-9lo, "e &'la$a &o" :ece" -" %e el G'erro. S' "ol&a-o" e( %(a arra &o" $'ra" 9aralela" &e e"$o" -e$ale" la cale($a-o", la -aor &'la$ac'( &el al%-'('o Gar %e la arra "e &ole Gac'a %( la&o "' la e(!r'a-o" oc%rr'r eac$a-e($e al co($rar'o. A9l'cac'o(e" '(&%"$r'ale". El c'l'(&ro &ee aH%"$ar 9er!ec$a-e($e e( "% ca-'"a. Para colocarlo "e lo e(!ra e( oe(o l%'&o "e lo coloca -'e($ra" e"$ co($ra&o, al &'la$ar"e rec%9erar la $e-9era$%ra a-'e($e %e&a !'r-e-e($e "%He$o e( "% l%ar. E'"$e( a" -%cGo" &'"%($ore", %e cor$a( la corr'e($e el*c$r'ca, o a9ara$o" %e &e"e(ca&e(a( alú( o$ro 9roce"o, c%a(&o la $e-9era$%ra llea a %( 9%($o cr$'co. El co(oc'-'e($o &el coe!'c'e($e &e &'la$ac'( a&%'ere %(a ra( '-9or$a(c'a $*c('ca e( -%cGa" rea" &el &'"eKo '(&%"$r'al. U( %e( eHe-9lo "o( lo" r'ele" &el !errocarr'l e"$o" :a( "ol&a&o" %(o" co( o$ro", 9or lo %e 9%e&e( llear a $e(er %(a lo('$%& &e :ar'o" ce($e(are" &e -e$ro". S' la $e-9era$%ra a%-e($a -%cGo la :a !*rrea "e &e"9laara 9or e!ec$o &e la &'la$ac'(, &e!or-a(&o co-9le$a-e($e el $raa&o. Para e:'$ar e"$o, "e e"$'ra el carr'l ar$'!'c'al-e($e, $a($o" ce($-e$ro" co-o "' !%e"e %(a &'la$ac'( (a$%ral "e cor$a el "ora($e, 9ara :ol:er a "ol&arlo. A e"$e 9roce"o "e le co(oce co-o (e%$ral'ac'( &e $e("'o(e". %( :a"o al %e GacGa-o" a%a G'r:'e(&o r9'&a-e($e, 9%e&e e"$allar, e"$o "e &ee a %e la" 9are&e" '($er'ore" %e e"$( e( co($ac$o co( el a%a &'la$a( la e$er'or. No le &a $'e-9o.
-% &Enumere al#unas objeciones para usar el a#ua dentro de un tubo de vidrio como termómetro(
a@ Por la acc'( &el ca-'o &e $e-9era$%ra &el a%a "' "e 9a"a &el e"$a&o (a$%ral a Ger:'&a el $%o (o a%a($ara "e re:e($ara. @ La &e("'&a& &el a%a e" -e(o" &e("a %e la &el -erc%r'o e" &ec'r, (o a%a($ara lo -'"-o %e 9%e&e a%a($ar el -erc%r'o. c@ Por lo" co-9o(e($e" &el a%a, "% e"$a&o (a$%ral co( el $'e-9o (o 9er-a(ece &e '%al !or-a, e" &ec'r &el e"$a&o l%'&o co( el $'e-9o "e e:a9orara. .% &Cree usted que la dilatación del líquido + la del recipiente alcan/an la misma temperatura ma#nitud para una cierta temperatura(
No (ece"ar'a-e($e a %e &e9e(&'e(&o &el rec'9'e($e o &el l%'&o, lo" coe!'c'e($e" &e &'la$ac'( &e a-a" e9er'-e($o" "o( &'!ere($e", el l%'&o 9or "er -" &e("o %e %( rec'9'e($e &e c%al%'er -a$er'al al "o-e$er"e a %(a $e-9era$%ra, ca-'ara "% e"$a&o "'e(&o &'la$a&o o lleara -%cGo -" r9'&o a $al 9%($o %e (o Gar -" &'la$ac'( %e el rec'9'e($e. 0% &"uede a#re#arse calor a una sustancia sin 1acer que se eleve su temperatura(
S' "e 9%e&e arear calor a %(a "%"$a(c'a "'( %e "e "%a "% $e-9era$%ra. E"$o "%ce&e ca&a :e %e oc%rra %( ca-'o &e !a"e. Por eHe-9lo, el ca-'o &e !a"e &e l%'&o a :a9or e( el a%a oc%rre a lo" 844C. A a$- &e 9re"'(. M'e($ra" el a%a e"$e e( e%ll'c'(, "% $e-9era$%ra "e -a($'e(e !'Ha e( lo" 844C, a 9e"ar &e %e 9%e&e "e%'r aHo la lla-a &e %( -ecGero. 2% &De qué depende la capacidad calorífica de un cuerpo(
La ca9ac'&a& calor!'ca &e %( c%er9o, e" el coc'e($e e($re la ca($'&a& &e e(era calor!'ca $ra("!er'&a a %( c%er9o o "'"$e-a e( %( 9roce"o c%al%'era el ca-'o &e $e-9era$%ra %e e9er'-e($a. E( %(a !or-a -e(o" !or-al e" la e(era (ece"ar'a 9ara a%-e($ar 8 la $e-9era$%ra e( %(a &e$er-'(a&a ca($'&a& &e %(a "%"$a(c'a =%"a(&o el SI@. La ca9ac'&a& calor!'ca &e9e(&e a&e-" &e la $e-9era$%ra &e la 9re"'(.
3% &De qué depende el calor específico de una sustancia(
Se co("'&era %(a "%"$a(c'a '($e("':a, 9or lo %e e" re9re"e($a$':a &e ca&a "%"$a(c'a, -'e($ra" %e la ca9ac'&a& calor!'ca, &e la c%al &e9e(&e e" %(a 9ro9'e&a& e$e("':a e" re9re"e($a$':a &e ca&a c%er9o 9ar$'c%lar. $4% &De una explicación de por qué las re#iones costeras tienden a tener un clima m5s moderado que las que se encuentran tierra adentro(
La" re'o(e" co"$era" $'e(e( %( cl'-a -" -o&era&o 9or %e la" r'"a" -ar'(a" a$e(úa( el calor &%ra($e el &a la" r'"a" $erre"$re" l'-'$a( la 'rra&'ac'( (oc$%r(a. El a%a $'e(e -%cGa '(erc'a $*r-'ca, e" &ec'r, $ar&a -%cGo e( cale($ar"e, 9ero $a-'*( $ar&a -" e( e(!r'ar"e e( co-9arac'( co( la" rea" co($'(e($ale". Por e"$o la" -a"a" &e a%a "o( el -" '-9or$a($e ae($e -o&era&or &el cl'-a. $$% Si se sabe que una caloría 6 ,%$2, joule% Exprese esta caloría en todos los sistemas de unidades que tienen que ver con ener#ía% Ener#ía 7 potencia
8 W>G; 2.5M);6541/4.5348cal 8 a$->L; 848.2/3); /1.//cal 8 eV;8.54/>8480); 2.62cal 8 B$%; 8431); /3/cal "rocedimiento experimental Experiencia )%$: Co-o &e$er-'(ar el calor e"9ec!'co &el a%a a %(a $e-9era$%ra
&'!ere($e a %(a $e-9era$%ra a-'e($e. Da$o"# Ma"a &el a%a; /34-l; /.3>84 1;/.3>84 Te-9era$%ra '('c'al &el a%a; / oC; 244Y Te-9era$%ra !'(al &el a%a; 35 oC; 2/0Y
Var'ac'( &e la $e-9era$%ra; /0 oC; /0Y No$a# U"a(&o la ec%ac'( &e e(era $*r-'ca a9ro9'a&a, "e &e$er-'(a la e(era $*r-'ca co( re"9ec$o al :alor &el calor e"9ec!'co &el a%a '%al a 8. Re"%l$a&o" &e lo" clc%lo"# <; C>?T; ->Ce>?T <; =/.3>841@=8cal7>Y@=/0Y@ <; ./3>842cal Experiencia 89: Clc%lo &el coe!'c'e($e &e &'la$ac'(.
"arte !
Da$o"# Ma$er'al; Barra &e al%-'('o Te-9era$%ra '('c'al; /3 oC; /06Y Te-9era$%ra !'(al; 15 oC; 280Y Lo('$%&; 348--; 4.348Lo('$%& !'(al; 4.34/2Var'ac'( &e la arra ; 8.2--; 8.2>84 2T'e-9o; /5-'( ;4.12G Re"%l$a&o" &e lo" clc%lo"# ; ?L7L>?$; 4.34/2- 4.348-7=4.348-@=280Y /06Y@; 8./2>841Y8 "arte ;
Da$o"# Ma$er'al; Barra &e ro(ce Te-9era$%ra '('c'al; /6 oC ;248Y Te-9era$%ra !'(al; 06 oC ;28Y Lo('$%&; 348--; 4.348Lo('$%& !'(al; 4.3486Var'ac'( &e la arra; 6>84 1-
T'e-9o; /5.4/-'( ; 4.1225G Re"%l$a&o" &e lo" clc%lo"# ; ?L7 L>?T ; 4.3486- 4.348-7=4.348-@=28Y 248Y@; /./6>84 3Y8 !n5lisis de resultados
To&o "l'&o al "o-e$er"e a $e-9era$%ra" al$a" "e &'la$a, lo co($rar'o 9a"a "' "e e(!ra, e"$e "e e(coHe %( 9oco. E( el e9er'-e($o %e "e e(co($raa( la" &o" arra" &e &'"$'($o" -a$er'ale" e"$o "e c%-9l', &'la$(&o"e ca&a %(a a &'!ere($e $e-9era$%ra. Al calc%lar la e(era $*r-'ca re!ere($e al a%a, el re"%l$a&o arroHa&o 9or la ec%ac'( e"$ :'(c%la&o co( el :alor &e calor e"9ec!'co %e "e e(c%e($ra e( lo" l'ro" &e !"'ca &o(&e e"$e e" '%al a 8, 9or lo $a($o, el calor a"or'&o 9or el a%a &e'&o al -ecGero e"$ e9re"a&o e( el re"%l$a&o.
;iblio#rafía
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