Physics 1st part

1. ZvcMwZwe`¨v (Math of Thermodynamics in Physics)
1| †Kvb ZvcgvÎvq †mjwmqvm I dv‡ibnvBU †¯‹‡j GKB cvIqv
hvq?
Avgiv Rvwb,
9
32F
5
C 

9
32x
5
x 

160x5x9 
160x5x9 
160x4 
4
160
x


(Ans.)F40C40x 
2| GKwU ÎæwUc~b© _v‡g©vwgUv‡i wb¤§w¯’i we›`y 4°C Ges DaŸ© w¯’i
we›`y 98°C| _v‡g©vwgUviwU 51°C cvV w`‡j dv‡ibnvBU †¯‹‡j
ZvcgvÎv KZ n‡e?
g‡bKwi, cÖK…Z ZvcgvÎv = F
cÖkœg‡Z,
§wb¤DaŸ©
§wb¤ZvcgvÎvcÖvß





32212
32F
498
451
32212
32F






94
47
180
32F



94
18047
32F


3290F 
.)Ans(F122F 
50273K 
27350K 
K323K 
3| †Kvb& ZvcgvÎvq †mw›U‡MÖW I dv‡ibnvBU †¯‹‡j cv‡Vi cv_©K¨
10°nq?
awi, †mjwmqvm †¯‹‡j cvV, C= x
 dv‡ibnvBU †¯‹‡j cvV = 1010  xx ev, 10x
Avgiv Rvwb,
9
32F
5
C 
 1g †ÿ‡Î, †mjwmqvm †¯‹‡j cvV, C= x
Ges dv‡ibnvBU †¯‹‡j cvV, F = 10x
9
3210x
5
x 

110x5x9 
110x5x9 
110x4 
4
110
x


C5.27x 
dv‡ibnvBU †¯‹‡j, F5.17105.2710 x
wØZxq †ÿ‡Î, †mjwmqvm †¯‹‡j cvV, C= x
Ges dv‡ibnvBU †¯‹‡j cvV = 10x
9
3210x
5
x 

210x5x9 
110x5x9 
210x4 
4
210
x


C5.52x 
dv‡ibnvBU †¯‹‡j, F5.62105.5210 x
DËit -27.5°C I -17.5°F Ges -52.5°C I -62.5°F
4| wcóbhy³ GKwU wmwjÛv‡i wKQy M¨vm Ave× Av‡Q| M¨‡mi Pvc 400Pa-
G w¯’i †i‡L wm‡ó‡g ax‡i ax‡i 800J Zvckw³ mieivn Kivq 1200J
KvR m¤úvw`Z nq| M¨v‡mi AvqZb cwieZ©b Ges AšÍt¯’ kw³i cwieZ©b
wbY©q Ki|
Avgiv Rvwb,
Q = U +W
ev, U =Q W
ev, U =800J 1200 J
 U =400 J
AšÍ¯’t kw³i cwieZ©b FbvZ¥K nIqvi A_© wm‡÷‡gi AšÍ¯’t kw³ n«vm
cv‡e|
Avevi,
W = PV
P
W
V


3
m
400
1200
V 
3
m3V  (Ans.)
5| 27°C ZvcgvÎvi †Kvb wbw`©ó cwigvb M¨vm nVvr cÖmvwiZ n‡q wظb
AvKvi jvf K‡i| P~ovšÍ ZvcgvÎv KZ? [ =1.4]
Avgiv Rvwb,
1γ
22
1γ
1 VTVT 1


1γ
2
1γ
1
1
2
V
V
T
T



1γ
2
1
1
2
V
V
T
T








11.4
2
2V
V
300
T








K5.0300T 4.0
2 
(Ans.)C45.64-C273)-(227.36K227.36T2 
GLv‡b,
Pvc, P = 400Pa
Zvc, Q = 800J
KvR,W = 1200 J
U = ?
AvqZb cwieZ©b, V =?
GLv‡b,
C= F = x awi,
GLv‡b,
ZvcgvÎv, T1 = 27 ºC
= (27+273)K = 300K
AvqZb, V1 = V (awi)
AvqZb, V2 = 2V
ZvcgvÎv, T2 = ?
 =1.4
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opyright©
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Jam
al
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2. cÖ_g c‡Îi As‡Ki mgvavb 2
6| 1 evqygÛjxq Pv‡c †Kvb M¨vm‡K iæ×Zvcxq cÖwµqvq AvqZb
wظb Ki‡j H M¨v‡mi P~ovšÍ Pvc KZ n‡e?[   ]
Avgiv Rvwb,
γ
22
γ
11 VP=VP








2
1
12
V
V
PPev,
41.1
5
2
2
10013.1P 






V
V
ev,
41.15
2 5.010013.1P ev,
P2 = 38120.37 Pa (Ans.)
7| ¯^vfvweK ZvcgvÎv I Pv‡c †Kvb M¨vm‡K m‡gvò cÖwµqvq wظb
AvqZ‡b cÖmvwiZ Ki‡j H M¨v‡mi P~ovšÍ Pvc KZ n‡e?
Avgiv Rvwb,
2
22
1
11
T
VP
T
VP

21
211
2
VT
TVP
P 
V2273
273V76.0
P2



(Ans.)mHg38.0P2 
8| ¯^vfvweK Pv‡c 100 m3
AvqZ‡bi GKwU M¨v‡m 5×103
J Zvc
w`‡j M¨v‡mi AvqZb 100.2 m3
nq| H M¨v‡mi K…Z Kv‡Ri gvb
wbY©q Ki|
Avgiv Rvwb,
K…ZKvR W = PV
 W = PV2V1)
 W =1.013×105
(100.2 100)J
 W =1.013×105
× 0.2 J
 W =1.013×105
× 0.2 J
W = 20260 J (Ans.)
9| GKwU wmwjÛv‡ii g‡a¨ ivLv wKQy cwigvb M¨vm cwi‡e‡ki Dci
200 J KvR m¤úv`‡bi mgq cwi‡ek †_‡K 500 J Zvckw³ †kvlY
K‡i| M¨v‡mi AšÍ¯’t kw³i cwieZ©b KZ n‡e?
Avgiv Rvwb,
Q = U +W
 U = Q W
 U =  
U = J (Ans.)
AšÍ¯’t kw³i cwieZ©b abvZ¥K nIqvi A_© wm‡÷‡gi AšÍ¯’t kw³
e„w× cv‡e|
10| 27°C ZvcgvÎvi †Kvb wØcvigvbweK M¨v‡mi Pvc nVvr wظb Kiv nj,
Pvc cwieZ©‡bi ci ZvcgvÎvi cwieZ©b KZ n‡e?
Avgiv Rvwb,
γ
γ-1
22
γ
γ-1
1 PTPT 1

γ
γ-1
2
1
1
2
P
P
T
T







1.4
1.4-1
2
1
1
2
2P
P
T
T







2857.0
2
2
1
300
T








K2857.0
2 5.0300T 

K70.653T2 
.)(70.6570.65)30070.365(12 AnsCKKTTT 
11| GKwU K‡b©v Bwćbi Dr‡mi ZvcgvÎv 400K, GB ZvcgvÎvq GKwU
Drm ‡_‡K GwU 840J Zvc Mªnb K‡i Ges wms‡K 630J Zvc eR©b K‡i|
wms‡Ki ZvcgvÎv I Bwćbi Kg©`ÿZv wbY©q Ki|
Avgiv Rvwb,
%100
Q
QQ
1
21



%100
840
630840



%100
840
210

)Ans(%25
Avevi,Avgiv Rvwb,
%100
T
TT
1
21



%100
400
T400
%25 2



4
T400
25 2

2T400100 
100400T2 
(Ans.)00K3T2 
12| GKwU K‡b©v BwÄb 327°C Ges 27°C DòZvi g‡a¨ KvR Ki‡Q|
Gi Kg© `ÿZv KZ?
Avgiv Rvwb,
%100
T
TT
1
21



%100
600
300600



%1005.0 
%50 (Ans.)
GLv‡b,
evqygÛ‡ji Pvc,
P1 =1.013×105
Pa
AvqZb, V1 = V (awi)
AvqZb, V2 = 2V
Pvc, P2 = ?
 
GLv‡b,
ZvcgvÎv, T1 = 400K
Zvc, Q1 = 840 J
Zvc, Q2 = 630 J
Kg©`¶Zv, 
wm‡¼i ZvcgvÎv, T2 = ?
GLv‡b,
D”P Zvcvav‡ii ZvcgvÎv,
T1 = 327ºC
=(327+273)K
= 600 K
wb¤§ Zvcvav‡ii ZvcgvÎv,
T2 = 27ºC = (27+273)K
= 300 K
Kg©`¶Zv, 
GLv‡b,
Pvc, P1 = 0.76 m Hg
ZvcgvÎv, T1 =0ºC=(0+273)
= 273K = T2
AvqZb, V1 = V (awi)
AvqZb, V2 = 2V
Pvc, P2 =?
GLv‡b,
Pvc, P = 1.013×105
Nm-2
Avw` AvqZb, V1 = 100 m3
‡kl AvqZb, V2 = 100.2 m3
cÖhy³ Zvc, Q = 5×103
J
K…ZKvR W =?
GLv‡b,
‡kvwlZ Zvc, Q=500 J
K…ZKvR, W =200 J
AšÍ¯’t kw³i cwieZ©b, U= ?
GLv‡b,
ZvcgvÎv, T1 = 27 ºC
= (27+273)K = 300K
Pvc, P1 = P (awi)
 Pvc, P2 = 2P
ZvcgvÎv gvÎvi cwieZ©b ,
?12  TTT
wØcvigvbweK M¨v‡mi  
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opyright©
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Jam
al
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3. cÖ_g c‡Îi As‡Ki mgvavb 3
13| GKwU Bwćbi Kg© `ÿZv 65%| Gi wb¤§ Zvcvav‡ii
(MÖvn‡Ki) ZvcgvÎv 27°C | Gi D”P Zvcvav‡ii (Dr‡mi) ZvcgvÎv
wbY©q Ki|
Avgiv Rvwb,
100%
T
TT
65%
1
21



1
1
T
300T
100
65 

11 65T30000100T 
3000065T100T 11 
3000035T1 
35
30000
T1 
857.14KT1 
(Ans.)C584.14C273)-857.14(T1 
14| GKwU BwÄb 3400J Zvc MÖnb K‡i I 2400J Zvc eR©b K‡i|
BwÄbwU Øviv m¤úvw`Z Kv‡‡Ri cwigvb I Bwćbi `ÿZv wbY©q Ki|
Avgiv Rvwb,
.)Ans(J1000W
J)24003400(W
2
Q
1
QW



%100
1
Q
2
Q
1
Q



%100
3400
24003400



%100
3400
1000

)Ans(%41.29
15| GKwU BwÄb 25°C Ges 225°C ZvcgvÎvi g‡a¨ Kvh©iZ|
Bwćbi Zvc Drm †_‡K 4200J Zvc MÖnb K‡i| BwÄb Øviv
m¤úvw`Z Kv‡Ri cwigvb wbY©q Ki|
Avgiv Rvwb,
2
1
2
1
T
T
Q
Q

1
21
2
T
TQ
Q 
498
2984200
Q2


J25.2513Q2 
Avevi,
21 QQW 
25.25134200W 
.)Ans(J74.1686W 
16| GKwU K‡Y©v BwÄb 800K I 400K Zvc gvÎvq †h `ÿZvq KvR
K‡i, wVK mg`ÿZvq KvR K‡i T K Ges 900K ZvcgvÎv| ZvcgvÎv T
wbY©q Ki|
Avgiv Rvwb,
%100
T
TT
1
21



%100
800
400800



%1005.0 
%50
Avevi,
100%
T
TT
1
21



100%
T
009T
%50 


2
T
009T
1 


T1800T2 
.)(1800T AnsK
17| 10°C ZvcgvÎvi 5kg cvwb‡K 100°C ZvcgvÎvq DËxY© Ki‡Z
G›Uªwci cwieZ©b wbY©q Ki|
Avgiv Rvwb,

2
1
T
T T
dQ
dS

2
1
T
T T
msdT
dS



2
1
T
T T
dT42005
dS
 
2
1
T
T
nT21000dS l
)TlnT(ln21000dS 12 
1
2
T
T
ln21000dS 
283
373
ln21000dS 
276131522.021000dS 
.)Ans(JK76.5798dS 1

GLv‡b,
wb¤§ Zvcvav‡ii ZvcgvÎv,
T2 = 27ºC
= (27+273)K
= 300 K
Kg©`¶Zv, 
D”P Zvcvav‡ii
ZvcgvÎv, T1 = ?
GLv‡b,
Zvc, Q1 = 3400 J
Zvc, Q2 = 2400 J
KvR, W =?
Kg©`¶Zv, 
GLv‡b,
D”P Zvcvav‡ii ZvcgvÎv,
T1 = 225ºC
= (225+273)K
= 498 K
wb¤§ Zvcvav‡ii ZvcgvÎv,
T2 = 25ºC
= (25+273)K
= 298 K
M„nxZ Zvc, Q1 = 4200J
K…Z KvR, W =?
GLv‡b, 1g †¶‡Î
D”P Zvcvav‡ii ZvcgvÎv,
T1 = 800K
wb¤§ Zvcvav‡ii ZvcgvÎv,
T2 = 400K
Kg©`¶Zv, 
GLv‡b, 2q †¶‡Î
wb¤§ Zvcvav‡ii ZvcgvÎv,
T2 = 900K
Kg©`¶Zv, 
D”P Zvcvav‡ii ZvcgvÎv,
T1 = T=?

GLv‡b,
fi, m = 5kg
ZvcgvÎv,T1 = 10ºC
=(273+10)K=283K
ZvcgvÎv,T2 = 100ºC
=(273+100KC=373K
G›Uªwci cwieZ©b dS=?

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opyright©
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Jam
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http://teachingbd.com

4. cÖ_g c‡Îi As‡Ki mgvavb 4
18| 0°C ZvcgvÎvi 3kg eid‡K 0°C ZvcgvÎvi cvwb‡Z cwiYZ
Ki‡Z GbUªwci cwieZ©b KZ n‡e? [eid Mj‡bi Av‡cwÿK myßZvc
=336000 Jkg-1
]
Avgiv Rvwb,
T
dQ
dS 
ev,
T
m
dS fl

ev,
273
3360003
dS


1
JK3.3692dS 
 (Ans)
19| 0°C ZvcgvÎvi 1kg cvwb‡K 100°C ZvcgvÎvq DËxY© Ki‡Z
G›Uªwci cwieZ©b wbY©q Ki|
Avgiv Rvwb,

2
1
T
T T
dQ
dS

2
1
T
T T
msdT
dS



2
1
42001T
T T
dT
dS
 
2
1
T
T
nT4200dS l
)TlnT(ln4200dS 12 
1
2
T
T
ln4200dS 
273
373
ln4200dS 
312106624.04200dS 
.)Ans(JK84.1310dS 1

20| GKwU Kv‡b©v Bwćbi Zvc MÖvn‡Ki ZvcgvÎv 7°C Ges `ÿZv 50%|
Bwćbi `ÿZv 60% Ki‡Z n‡j Zvc Dr‡mi ZvcgvÎv KZ e„w× Ki‡Z
n‡e?
Avgiv Rvwb,
100%
T
TT
1
21
1 


100%
T
802T
50%
1
1



1
1
T
082T
100
50 

11 T0500082100T 
0008250T1 
50
28000
T1 
K605T1 
100%
T
TT
/
1
2
/
1
2 


100%
T
802T
60% /
1
/
1



/
1
/
1
T
082T
100
60 

/
1
/
1 T0600082100T 
0008240T/
1 
40
28000
T/
1 
K700T/
1 
ZvcgvÎv e„w×
= 140KK)560700(TT 1
/
1  ev, 140°C (Ans.)
.)(41.329/
2
/
1 AnsHzff 
GLv‡b,
ei‡di fi, m = 3kg
Mj‡bi Av‡cw¶K myßZvc
lf=336000 Jkg-1
|
ZvcgvÎv T= (0+273)K=273 K
GbUªwci cwieZ©b dS=?
GLv‡b,
fi, m = 1kg
ZvcgvÎv, T1 = 0ºC
=(273+0)ºK=273ºK
ZvcgvÎv, T2 = 100ºC
=(273+100)ºK=373ºK
G›Uªwci cwieZ©b dS=?

GLv‡b,
MÖvn‡Ki ZvcgvÎv,
T2 = 7ºC
= (7+273)K
= 280 K
Kg©`¶Zv, 
Dr‡mi ZvcgvÎv, T1 =?
Kg©`¶Zv, 
?TT 1
/
1  
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