ICSE Class 10 Physics 2014 Solved Paper

Question : 55

Total: 66

Heat energy is supplied at a constant rate to 100g of ice at 0∘C. The ice is converted into water at 0∘C in 2 minutes. How much time will be required to raise the temperature of water from 0∘C to 20∘C ? [Given : sp. heat capacity of water =4.2Jg−1‌∘C−1, sp. latent heat of ice =336Jg−1].

Solution:

Given : m=100g,t=2 minutes =2×60 sec.
Heat energy taken by ice at 0∘C to convert to water at 0∘C.
‌Q=mL=100×336=33600J
‌∴‌‌P=‌

=‌

33600

2×60

=280J∕ s
The heat energy required to convert water at 0∘C to 20∘C .
Q‌=mc∆t=100×4.2×20=8400J
Q‌=P×t
8400‌=280×t
t‌=30 sec=0.5‌min.

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