Q. No.In 5 minutes, a body cools from \(75^\circ \text{C}\) to \(65^\circ \text{C}\) at room temperature of \(25^\circ \text{C}.\) The temperature of the body at the end of the next \(5\) minutes is:
1. \(37^\circ\text C\)
2. \(46^\circ\text C\)
3. \(57^\circ\text C\)
4. \(66^\circ\text C\)
1. \(37^\circ\text C\)
2. \(46^\circ\text C\)
3. \(57^\circ\text C\)
4. \(66^\circ\text C\)
Subtopic: Newton's Law of Cooling |
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A certain quantity of water cools from 70 0C to 60 0C in the first 5 minutes and to 54 0C in the next 5 minutes. The temperature of the surroundings is:
1. 45oC
2. 20oC
3. 42oC
4. 10oC
Subtopic: Newton's Law of Cooling |
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A body takes \(4 ~\text{min}\) to cool from \( 61^\circ \text C\) to \( 59^\circ \text C.\) If the temperature of the surroundings is \( 30^\circ \text C,\) the time taken by the body to cool from \( 51^\circ \text C\) to \( 49^\circ \text C\) is:
1. \(6~\text{min}\)
2. \(3~\text{min}\)
3. \(4~\text{min}\)
4. \(8~\text{min}\)
1. \(6~\text{min}\)
2. \(3~\text{min}\)
3. \(4~\text{min}\)
4. \(8~\text{min}\)
Subtopic: Newton's Law of Cooling |
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A pan filled with hot food cools from \(95^\circ\text{C}\) to \(85^\circ\text{C}\) in \(2\) minutes when the room temperature is \(20^\circ\text{C}.\) The time taken by the food to cool from \(55^\circ\text{C}\) to \(45^\circ\text{C}\) will be:
1. \(260~\text s\)
2. \(280~\text s\)
3. \(300~\text s\)
4. \(320~\text s\)
1. \(260~\text s\)
2. \(280~\text s\)
3. \(300~\text s\)
4. \(320~\text s\)
Subtopic: Newton's Law of Cooling |
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A body cools from \(62^{\circ}\text{C}\) to \(50^{\circ}\text{C}\) in \(10\) min and to \(42^{\circ}\text{C}\) in the next \(10\) min. The temperature of the surrounding is:
1. \(16^{\circ}\text{C}\)
2. \(26^{\circ}\text{C}\)
3. \(36^{\circ}\text{C}\)
4. \(21^{\circ}\text{C}\)
1. \(16^{\circ}\text{C}\)
2. \(26^{\circ}\text{C}\)
3. \(36^{\circ}\text{C}\)
4. \(21^{\circ}\text{C}\)
Subtopic: Newton's Law of Cooling |
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Given below are two statements:
| Assertion (A): | For small difference in absolute temperature, compared with the temperature itself, the net rate of transfer of energy from a body to its surrounding by radiation is directly proportional to the temperature difference. |
| Reason (R): | The net ratio of transfer of energy by radiation from a body (temperature \(T_b=T_S+\theta\)) to its surrounding (temperature \(T_S\)) is given by: \(\dfrac{dQ}{dt}=eA\sigma(T_b^4-T_S^4)\\ ~~~~~~~=eA\sigma\left\{(T_S+\theta)^4-T_S^4\right\}\\ ~~~~~~~\approx4eA\sigma T^3_S\theta,~\text{where }\theta\ll T_S.\) |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
Subtopic: Newton's Law of Cooling |
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A pan filled with hot food cools from \(95^\circ \text{C}\) to \(85^\circ \text{C}\) in \(2\) min when the room temperature is \(20^\circ \text{C}.\) The time taken by the food to cool from \(55^\circ \text{C}\) to \(45^\circ \text{C}\) will be:
| 1. | \(260\) s | 2. | \(280\) s |
| 3. | \(300\) s | 4. | \(320\) s |
Subtopic: Newton's Law of Cooling |
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It is observed that the temperature of a well-insulated body drops by \(0.1^\circ\text C\) in \(2\) mins, when the temperature of the body is \(50^\circ\text C\) and the room temperature is \(20^\circ\text C.\) How much time will be required for the temperature of the same body to fall from \(36^\circ\text C\) to \(34^\circ\text C,\) the room temperature remaining the same?
1. \(20\) min
2. \(40\) min
3. \(80\) min
4. \(160\) min
1. \(20\) min
2. \(40\) min
3. \(80\) min
4. \(160\) min
Subtopic: Newton's Law of Cooling |
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The temperature of a body falls from 50 to 40 in 10 minutes. If the temperature of the surroundings is 20, then temperature of the body after another 10 minutes will be-
(1) 36.6
(2) 33.3
(3) 35
(4) 30
Subtopic: Newton's Law of Cooling |
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A body cools down from \(65^\circ \text{C}\) to \(60^\circ \text{C}\) in \(5\) minutes. It will cool down from \(60^\circ \text{C}\) to \(55^\circ \text{C}\) in:
| 1. | \(5\) minutes |
| 2. | less than \(5\) minutes |
| 3. | more than \(5\) minutes |
| 4. | less than or more than \(5\) minutes depending on whether its mass is more than or less than \(1~\text{kg}\) |
Subtopic: Newton's Law of Cooling |
80%
Level 1: 80%+
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