Question

10 lit of hot water is taken in a bucket.the amount of cold water at 20DEG to be added to the bucket to obtainwater at 35DEG is ?

Answer 1

Answer:

Correct option is B)

m (hot water) =10kg,

T (hot water) =70

o

C

m (cold water) =20kg

T (cold water) =20

o

C,T(final)=?

Using the formula Q=mCΔt

We get heat lost by hot water

=10×C×(70−T

f

)

Where T

f

is the final temperature

Heat gained by cold water

=20×C×(T

f

−20)

Using the principle of calorimetry

Heat lost = Heat gained

We get 10×C×(70−T

f

)

=20×C×(T

f

−20)

∴700−10T

f

=20T

f

−400

or 30T

f

=1100∴T

f

=36.67

o

C.