Question

A dealer purchased 124 LED sets.If the cost of one set is Rupees 38,540, determine their total cost.

Answer 1

Answer:

For Hot water:

Mass=40g

S.H.C=4.2Jg

−1

o

C

−1

InitialTemp.=60

o

C

FinalTemp.=x

△T

H

=(60−x)

for Cold water:

Mass=100g

S.H.C=4.2Jg

−1

o

C

−1

InitialTemp.=?

FinalTemp.=x

△T

C

=10

o

C

Heatgivenoutbyhotwater=mc△T

H

=40×4.2×(60−x)

Heatabsorbedbycoldwater=mc△T

C

=100×4.2×10

∴Heatgivenoutbyhotwater=Heatabsorbedbycoldwater

∴40×4.2×(60−x)=100×4.2×10

2400−40x=1000

40x=2400−1000

∴x=

40

1400

=35

o

C

Thus,final temperatureofmixture=35

o

C

Initialtemperatureofcoldwater=(35−10)=25

o

C

Sothecorrectansweris25