Question 18
Quantity of HeatA tap supplies water at 25°C while another supplies water at 75°C. If a man wishes to bathe with water at 40°C, the ratio of the mass of cold water to the mass of hot water required is
- A.1 : 3
- B.15 : 8
- C.7 : 3
- D.3 : 1
Show the answer and explanation
Answer: C (7 : 3)
Explanation
Heat lost by hot = heat gained by cold: mh × 35 = mc × 15, so mc : mh = 35 : 15 = 7 : 3.