Mehlala e 5 ea mathata a mocheso
1. Thine e boima ba lik'hilograma tse 2 e na le mocheso o itseng oa 130 J.kg -1 C -1 . Palo ea mocheso o monngoang ke thine ho phahamisa mocheso oa eona ho tloha ho 50 o C ho isa ho 100 o C ke….
Puisano
Hoa tsebahala hore:
Boima (m) = 2 kg
Mocheso o itseng oa thini (c) = 130 J.kg -1 C -1
Phetoho ea mocheso (Δ T) = 100 o C – 50 o C = 50 o C
Potso: Mocheso (Q) o monngoa ke thini
Karabo:
Foromo ea mocheso:
Q = mc Δ T
Tlhaloso: Q = mocheso, m = boima, c = mocheso o itseng, Δ T = phetoho mochesong
Mocheso o monngoang ke thini:
Q = (2 kg)(130 J.kg -1 C -1 )(50 o C)
Q = (100)(130)
Q = 13000 Joule
Q = 1,3 x 10 4 Joule
2. Koporo e nang le mocheso o itseng oa 390 J kg -1 o C -1 e ba le phetoho ea mocheso oa 40 o C. Haeba mocheso o monngoang ke koporo nakong ea phetoho ea mocheso e le lik'hilojule tse 200, joale boima ba koporo ke...
Puisano
Hoa tsebahala hore:
Mocheso o itseng oa koporo (c) = 390 J kg -1 o C -1
Phetoho ea mocheso (Δ T) = 40 o C
Mocheso (Q) = 40 Joule
Potso: Boima (m) ba koporo
Karabo:
Q = mc Δ T
40 = (m)( 390 )(40 o C)
40 = (m)(390 )(40)
40 = (m)( 390 )(4)
40 = (m)( 1560 )
m = 40 / 1560
m = 0,026 kg
Boima ba koporo ke digrama tse 26.
3. Metsi a boima ba digrama tse 20 ka mocheso o itseng wa 1 cal g -1 o C -1 qalong a na le mocheso wa 30 o C. Fumana phetoho mochesong wa metsi haeba mocheso o monngwang ke metsi e le dikhalori tse 300!
Puisano
Hoa tsebahala hore:
Boima (m) = 20 gr
Mocheso oa pele (T 1 ) = 30 o C
Mocheso o itseng oa metsi (c) = 1 cal gr -1 o C -1
Mocheso (Q) = 300 cal
E botsitsoe: Liphetoho mochesong oa metsi
Karabo:
Q = mc Δ T
Q = mc (T 2 – T 1 )
300 cal = (20 gr)( 1 cal gr -1 o C -1 )(T 2 – 30 o C)
300 = (20)(1)(T 2 - 30)
300 = 20 (T 2 - 30)
300 = 20 T 2 – 600
300 + 600 = 20 T 2
900 = 20 T 2
T 2 = 900 / 20
T 2 = 45 o C
Liphetoho tsa mocheso:
Δ T = 45 o C – 30 o C
ΔT = 15 o C
4. Palo ea mocheso o hlokahalang ho theola mocheso oa 4 kg ea mokelikeli o nang le mocheso o itseng oa 500 J/kg K ho tloha ho 40 oC e ba 20 oC ke…
A. 20 kJ
B. 30 kJ
C. 40 kJ
D. 50 kJ
E. 60 kJ
Puisano:
Hoa tsebahala :
Boima (m) = 4 kg
Mocheso o itseng (c) = 500 J/kg K = 500 J/kg Co
Phetoho ea mocheso (delta T) = 40 oC - 20 oC = 20 Co
E botsitsoe :
Mocheso (Q)
Jawab :
Foromo ea Mocheso :
Q = (m)(c)(delta T)
Q = (4)(500)(20) = 40.000 Dijoule = 40 kJ
kJ = kilo Joule
Karabo e nepahetseng ke C.
5. Ntho e tiileng e boima ba 2 kg e futhumatsoa ho tloha mochesong oa 30oC e ba 100oC, e hloka mocheso oa 7 × 105 Joule. Mocheso o itseng oa ntho ke…
A. 400 J/kg K
B. 500 J/kg K
C. 700 J/kg K
D. 1000 J/kg K
E. 5000 J/kg K
Puisano:
Hoa tsebahala :
Boima (m) = 2 kg
Mocheso (Q) = 7 × 105 J = 700.000 J
Phetoho ea mocheso (delta T) = 100 oC - 30 oC = 70 Co
E botsitsoe :
Mocheso o itseng (c)?
Jawab :
c = Q / m T
c = 700.000 J / (2 kg)(70 Co) = 700.000 J / 140 kg Co
c = 5000 J/kg Co
c = 5000 J/kg K
Karabo e nepahetseng ke E.
