2 kg of substance receives 500 kJ and undergoes a temperature change from 100°C to 200°C. The average specific heat of substance during the process will be

Question

Question

This question was previously asked in

ISRO VSSC Technical Assistant Mechanical 8 Feb 2015 Official Paper

Answer 1

Concept:

When Q joule heat is added to a body whose mass is m, the temperature rises from T₁ to T₂.

It is given by Q = mc(T₂- T₁) where c = specific heat of the body.

Calculation:

Given:

m = 2 kg, Q = 500 kJ, T₂ = 200 °C, T₁ = 100 °C

∵ Q = mc(T₂ – T₁)

⇒ 500 = 2 × c × (200 – 100)

⇒ c = 2.5 kJ/kg°K

Important Points

When difference of temperature is needed do not convert °C into °K.