SATHEE: Properties Of Solids And Liquids Question 458

Properties Of Solids And Liquids Question 458

Question: A body cools in a surrounding of constant temperature $39^{\circ} C$ . Its heat capacity is $2 J / k g^{\circ} C$ . Initial temperature of the body is $49^{\circ} C$ . Assume Newton’s law of cooling is valid. The body cools to $38^{\circ} C$ in 19 minutes. In further 19 minutes it will cool from $38^{\circ} C$ to

Options:

A) $36^{\circ} C$

B) $36.4^{\circ} C$

C) $37^{\circ} C$

D) $37.5^{\circ} C$

Show Answer

Answer:

Correct Answer: B

Solution:

[b] We have $θ - θ_{s} = (θ_{0} - θ_{s}) e^{- k t}$ ….(l)

where $θ_{0}$ = initial temperature of body $= 40^{\circ} C$

$θ =$ temperature of body after time t $θ_{s} =$ temperature of surrounding Since body cools from $40^{\circ} C t o 38^{\circ} C$ in 10 min, we have $38^{\circ} - 30^{\circ} = (40^{\circ} - 30^{\circ}) e^{- 10 k}$ ….(2)

Let after 10 min, the body temp. be $θ$ .

$θ - 30^{\circ} = (38^{\circ} - 30^{\circ}) e^{- 10 k}$ …..(3)

Dividing equ. (2) by equ. (3) gives, $\frac{8^{o}}{θ - 30^{o}} = \frac{10^{o}}{8^{o}} \Rightarrow θ - 30^{o} = {6.4}^{o} \Rightarrow θ = 36. 4^{o}$

Properties Of Solids And Liquids Question 458

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Properties Of Solids And Liquids Question 458

Question: A body cools in a surrounding of constant temperature 39∘C . Its heat capacity is2J/kg∘C . Initial temperature of the body is49∘C . Assume Newton’s law of cooling is valid. The body cools to 38∘C in 19 minutes. In further 19 minutes it will cool from 38∘C to

Options:

Answer:

Solution:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

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