Question

If 100g of water at 40°c temperature and 150g of water at 80°c temperature are mixed, what is the final temperature?

Answer 1

let final temperature is ∅
here 150gm of water will be loss heat and 100gm of water will be gain.
now,
heat Loss = heat gain
use H = ms∆T

m1S( 80° -∅ ) = m2S(∅ -40°)
150( 80° -∅) = 100 ( ∅ -40°)
3( 80° -∅) = 2( ∅ -40°)
240° -3∅ = 2∅ -80°
320° = 5∅
∅ = 320/5 = 64° C

hence final temperature = 64°

Answer 2

mc∆t = mc∆t ( formula )

Given :
Hot body Cold body
m = 150 m = 100
c = c c = c
t = 80°c t = 40°


Solution:
150 × c × (80-t) = 100 × c × (t-40)
3 (80-t) = 2 (t-40)
240 - 3t = 2t - 80
320 = 5t
T = 64°c
Therefore the final temperature is 64°c.


Hope it helps.................