JEE Physics

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Chapter 28 Experiment - Newton'S Law Of Cooling - all with Video Answers

Educators

Chapter Questions

02:07

Problem 2819

A liquid takes 5 minute to cool from $80^{\circ} \mathrm{C}$ to $50^{\circ} \mathrm{C}$. The temperature of the surrounding is $20^{\circ} \mathrm{C}$. What is the time it will take to $\operatorname{cool}$ from $60^{\circ} \mathrm{C}$ to $30^{\circ} \mathrm{C}$ ?
(A) $9 \mathrm{~min}$
(B) $5 \mathrm{~min}$
(C) $12 \mathrm{~min}$
(D) $6 \mathrm{~min}$

Khoobchandra Agrawal

Numerade Educator

01:09

Problem 2820

Two spheres of the same material have radii $1 \mathrm{~m}$ and $4 \mathrm{~m}$ and temperatures $2000 \mathrm{k}$ and $4000 \mathrm{k}$ respectively. If the energy radiated by the spheres are $E_{1}$ and $E_{2}$ respectively then find ratio of $\left(\mathrm{E}_{1} / \mathrm{E}_{2}\right)$
(A) $1: 256$
(B) $256: 1$
(C) $16: 1$
(D) $1: 16$

Narayan Hari

Numerade Educator

02:32

Problem 2821

A body cools in 5 minute from $60^{\circ} \mathrm{C}$ to $40^{\circ} \mathrm{C}$. The temperature of the surroundings is $10^{\circ} \mathrm{C}$. What is its temperature after the next 5 minute?
(A) $32^{\circ} \mathrm{C}$
(B) $24^{\circ} \mathrm{C}$
(C) $28^{\circ} \mathrm{C}$
(D) $30^{\circ} \mathrm{C}$

Khoobchandra Agrawal

Numerade Educator

01:02

Problem 2822

What is the units of emissive power in stefan's law?
(A) $\mathrm{Ws}^{-1}$
(B) W
(C) $\mathrm{Ws}^{-1} \mathrm{~m}^{-2}$
(D) $\mathrm{Wm}^{-2}$

Narayan Hari

Numerade Educator

01:16

Problem 2823

A sphere, a cube and a thin circular plate are all made of the same material, have the same mass and are initially heated to a temperature of $200^{\circ} \mathrm{C}$. Arrange then in the ascending order of rate of cooling.
(A) sphere, plate, cube
(B) sphere, cube, plate
(C) cube, sphere, plate
(D) plate, cube, sphere

Narayan Hari

Numerade Educator