lab. n8

7/17/2019 lab. n8

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UNIVERSIDAD NACIONAL MAYORDE SAN MARCOS

(Universidad del Perú, Decana de América

!ac"l#ad de Ciencias !$sicas

E%A%P% IN&ENIER'A MECNICA DE!LUIDOS

C"rs)* La+)ra#)ri) de !$sica

Semes#re*-./0II

Pr)1es)r* Car)lina 2r"3ill) Saen4

2ra+a3)* In1)rme N) 5

2"rn)* 6"eves .-0. 7m

Al"mn)*

ALVARADO 8UAMN, 6ULIO .9.9--9/

DVILA :AL:'N, 6UNIOR .9.9--5;

YARI !ERNADE<, SAMUEL.9.9--;=

OLIVERA MERLO, ELVIS .9.9-.->

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-./A:SORCION DE CALOR

(Experiencia N° 8)

I% O+3e#iv)s*

Investigar el comportamiento de la energía térmica absorbida/disipadapor una sustancia líquida.

acer un estudio comparativo de la cantidad de calorabsorbido/disipado para di!erentes proporciones del líquido.

Investigar c"mo se transporta el calor en los #uidosII% E?UIPOS @ MA2ERIALES

Cal)r a+s)r+id) 0 Disi7ad)

$ %ec&ero bunsen $ 'oporte universal $ lamp $ erm"metro $ *gitador $ +aso de precipitado graduado de ,-- cc. $ +aso de precipitado de -- cc. apel milimetrado apel toalla

C)nveccin $ %ec&ero bunsen

$ 'oporte 0niversal $ lamp $ erm"metro $ in1a universal $ +aso de precipitado de -- cc. $ uc&ara de mango (esp2tula) ermanganato de potasio Espiral de papel preparado

III% !"ndamen#) 2eric)*Cas) .* CALOR A:SOR:IDO Y DISIPADO

3a energía térmica que gana o pierde un cuerpo de masa m es

directamente proporcional a su variaci"n de temperatura.Esto es4

Qαm(T −T o)

Q=mc (T −T o) 5onde44 calor especí6co.

o4 temperatura inicial de re!erencia.

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4 temperatura 6nal.El suministro de energía térmica por unidad de tiempo a un cuerpo7corresponde a que este reciba un #uo calorí6co H. 'i el #uo esconstante7

H =dQ

dt

=cte

5e ($) 9 () se tiene4dQ

dt =mc

dT

dt = H 7

3uego

dT = H

mc dt

Integrando e iterando se tiene4

∫T

0

T

dT = H

mc∫0

t

dt

T = H mc

t +T 0

3a ecuaci"n (:) relaciona la temperatura con el tiempo. Es una !unci"n

lineal7 donde H

mc representa la pendiente 9 o la temperatura inicial.

'i el cuerpo se encuentra en un sistema adiab2tico7 el trabao dedilataci"n se reali1a a expensas de la energía interna.

'in embargo7 la variaci"n de la energía en el interior del cuerpo enun proceso no coincide con el trabao reali1ado; la energíaadquirida de esta manera se denomina cantidad de calor7 es

positivo cuando absorbe calor 9 negativo cuando disipa calor. 3a energía interna del cuerpo aumenta a costa de la cantidad de

calor adquirida dq7 9 disminu9e a costa del trabao reali1ado porel cuerpo dw (principio de conservaci"n de la energía en losprocesos térmicos). 'e le conoce como la primera le9 de latermodin2mica 9 se expresa como4

dU =dQ− PdV

Cas) * CONVECCIBN3a propagaci"n del calor se puede dar por tres métodos di!erentes4

conducci"n (ens"lidos)7 convecci"n (en #uidos) 9 radiaci"n7 a través de cualquier mediotransparentea ella. 'i &a9 di!erencia de temperatura entre dos puntos7 el calorsiempre se propagade la 1ona m2s caliente a la menos caliente.<N+EI=N4 Es la manera m2s e6ciente de propagaci"n del calor7 seda en los

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#uidos. 0n #uido c2lido7 por di!erencia de densidades7 asciende &aciaregiones menoscalientes; por compensaci"n un #uido !río desciende a tomar su lugar; sicontin>a asíeste movimiento7 da lugar a la !ormaci"n de células convectivas.

Eemplo7 cuando elagua &ierve se !orman burbuas (regiones calientes) que ascienden &aciaregionesmenos calientes7 las células convectivas en la atm"s!era que dan lugar alasprecipitaciones pluviales.

IV% Pr)cedimien#) e7erimen#al

M)n#a3e .* CALOR A:SOR:IDO@DISIPADO

$. %onte el equipo7 como muestra el dise?oexperimental.

. oloque @--gr de agua en el vaso pirex atemperatura del ambiente.

:. Encienda el mec&ero. %antenga el #uo de calorconstante durante toda la experiencia. 3a llama nodebe ser mu9 !uerte ni estar mu9 cerca al vaso.

@. *gite el agua previamente 9 lea la temperatura cada:-s &asta llega al punto de ebullici"n. *note los datosen la abla No$.

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,. Aepita los pasos ($) al (@) bao las mismas condiciones anteriores; peroa&ora para la mitad de la cantidad de agua que la anterior. *note los datosen la abla .

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B. Cra6que la variaci"n de temperatura versus el tiempo t7 para los doscasos anteriores. (0se papel milimetrado)

D. 5etermine la ecuaci"n de la gr26ca por el método de mínimos cuadrados7considerando la temperatura &asta D,-. 5e los gr26cos "moidenti6caría el líquido que tiene ma9or masaF

8. +ierta esta agua caliente en la probeta graduada &asta -- ml. 3uegoviértalo en el vaso de espuma de poliuretano. oloque un term"metro enel vaso de espuma 9 tome la temperatura del agua cada $- s durante @minutos. *note los datos en la tabla :.

G. 'eque un cubo de &ielo con una toalla de papel e introd>1calo en el agua.$-.ontin>e tomando la temperatura cada $-s7 &asta @ minutos después que

el cubo de &ielo se &a9a !undido. *note los datos en la tabla @.

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$$.

De#ermine el v)l"men nal del a"a% Va"a ( nal F GGGGG%

H?"é masa #en$a el a"a )riinalmen#e ma"a ()riinal F GGGGG%

H?"é masa #en$a el Jiel) )riinalmen#e mJiel) ()riinal F GGGGG%

E7liK"e Hcm) de#ermin es#as masas

$.aga una gr26ca de versus t. (papel milimetrado)

M)n#a3e * CONVECCION(A&UA

$. En el vaso de precipitados vierta alrededor de @-- ml de agua.. or el borde del vaso de precipitados dee caer en el agua algunos

cristales de ermanganato pot2sico.:. on la llama baa coloque el mec&ero debao del borde in!erior del vaso

de precipitados.@. %ientras se calienta7 observe atentamente el agua coloreada. *note sus

impresiones.

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HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH.HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH.HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH.HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH.

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,. En la 6gura 7 se?ale el camino recorrido por el agua coloreada.Explique lo que observa mientras se calienta el agua...............................................................................................................................................................................................................................................................................

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....................................................................................................................

...................HHHHHH.HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH.HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH.HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH.HHHHHH

MON2A6E 9% CONVECCIBN (EN AIRE

$) 5esglose la &oa con las 6guras de espirales 9 recorte cuidadosamente.) aga un nudo en el sedal 9 p2selo por un ori6cio previamente &ec&o en

el centro de la espiral. (igura :).

:) Encienda el mec&ero con una llama baa.@) uelgue la espiral entre $, 9 - cm por encima del mec&ero.,) <bserve atentamente el !en"meno. *note sus impresiones.HHHHHH.HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH.HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHara la espiral con!eccionada del otro sentido7 el giro sería el mismoF or

quéFHHHHHH.HHHHHHHHHHHHHHHHHHHHHHHH.HHHHHHH.HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

B) 'e?ale tres eemplos en los que se observe este !en"meno.

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a. HHHHHH.HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH.b.HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

c.HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH.

V% Eval"acin*

.% Si en l"ar de a"a, se "#ili4a )#r) l$K"id) de ma)r cal)r

es7ec$c), 7er) de i"al masa, HCm) ser$a el rc) 2rcel) descr$+al)%

7/17/2019 lab. n8


GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

7/17/2019 lab. n8


GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGG

% HP)r K"é en el a3"s#e de la rca n) se c)nsidera el in#erval) de=)C a .--)CGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

9% De#ermine el "3) cal)r$c) en cada cas)% !$sicamen#e, Ha K"ién

se de+e dicJ) val)r

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/% IndiK"e el #iem7) K"e dem)r en rec)rrer el in#erval) 5-C 5=C%Revise el cas) reis#rad) en#re =-C ==C%

7/17/2019 lab. n8


=% H?"é relacin eis#e en#re las 7endien#es de las di1eren#es

rcas la can#idad de cal)r a+s)r+ida 7ara l)s di1eren#escas)sGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

;% Inves#i"e e7liK"e s)+re la c)nveccin 1)r4ada, de e3em7l)s dea7licacin%GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

7/17/2019 lab. n8


% L)s m)#)res a"#)m)#rices n) 7"eden re1rierarse 7)r si s)l)s,H?"é sis#emas "san K"e 7rinci7i) de 7r)7aacin "san 7aradisi7ar la ener$a cal)r$caGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

5% En las minas s"+#errneas se 7resen#a el 7r)+lema de lacirc"lacin de aire% Inves#i"e K"e sis#emas "san c)n K"é7rinci7i) 1$sic) se desarr)llan%GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

7/17/2019 lab. n8


GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

>% Se sa+e K"e el S)l es# c)ns#i#"id) 7)r divers)s ases, inves#i"e"s#ed cm) )c"rre el #rans7)r#e de ener$a a #ravés de él%GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

GGGGGGGGGGGGGGGG

7/17/2019 lab. n8


VI% C)ncl"si)nes*

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HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

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lab. n8

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