Question

The specific heat of a substance varies as (3t^2+t) x 10^-3 cal/g-°C. What is the amount of heat
required in K Cal to raise the temperature of 1 kg of substance from 10°C to 20°C?

1) 2.15
2) 4.15
3) 7.15
4) 9.15​

Answer 1

answer : option (3) 7.150 KCal.

explanation : amount of heat required, H = $m\int\limits^{t_f}_{t_i}{s}\,dt$

here given, Tf = 20°C , Ti = 10°C , s = (3t² + t) × 10^-3 cal/g.°C and m = 1 kg = 1000g

= $m\int\limits^{20}_{30}{(3t^2+t)}\,dt$

= $10^3\times10^{-3}\times\left[\frac{3t^3}{3}+\frac{t^2}{2}\right]^{20}_{30}$ cal

= 1 × [(20³ - 10³) + (20² - 10²)/2] cal

= [7000 + 150 ] cal

= 7150 cal

= 7.150 Kcal

hence, amount of heat required = 7.150 Kcal

Answer 2

Answer:

hope you UNDERSTOOD this answer

Explanation:

7.150 is your answer