Q. No.The temperature of a body in air falls from \(40^\circ \text {C}\) to \(24^\circ \text {C}\) in \(4\) minutes. The temperature of the air is \(16^\circ \text {C}\). The temperature of the body in the next \(4\) minutes will be -
1. \(\dfrac {28}{3}^\circ \text {C}\)
2. \(\dfrac {42}{3}^\circ \text {C}\)
3. \(\dfrac {14}{3}^\circ \text {C}\)
4. \(\dfrac {56}{3}^\circ \text {C}\)
1. \(\dfrac {28}{3}^\circ \text {C}\)
2. \(\dfrac {42}{3}^\circ \text {C}\)
3. \(\dfrac {14}{3}^\circ \text {C}\)
4. \(\dfrac {56}{3}^\circ \text {C}\)
Subtopic: Newton's Law of Cooling |
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Level 2: 60%+
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A cup of coffee cools from \(90^{\circ} \text{C}\) to \(80^{\circ} \text{C}\) in \(t\) minutes when the room temperature is \(20^{\circ} \text{C}.\) The time taken by the similar cup of coffee to cool from \(80^{\circ} \text{C} \) to \(60^{\circ} \text{C} \) at the same room temperature is:
1. \(\dfrac{13}{10} t\)
2. \(\dfrac{10}{13} t\)
3. \(\dfrac{5}{13} t\)
4. \(\dfrac{13}{5} t\)
1. \(\dfrac{13}{10} t\)
2. \(\dfrac{10}{13} t\)
3. \(\dfrac{5}{13} t\)
4. \(\dfrac{13}{5} t\)
Subtopic: Newton's Law of Cooling |
Level 4: Below 35%
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The temperature of body drops from \(60^\circ \mathrm{C}\) to \(40^\circ \mathrm{C}\) in \(7\) min. The surrounding temperature is \(10^\circ \mathrm{C}.\) The temperature of body drops from \(40^\circ \mathrm{C}\) to \(\mathrm{T}^\circ \mathrm{C}\) in \(7\) min. The value of \(\mathrm{T}\) is:
1. \(16^\circ \mathrm{C}\)
2. \(20^\circ \mathrm{C}\)
3. \(28^\circ \mathrm{C}\)
4. \(36^\circ \mathrm{C}\)
1. \(16^\circ \mathrm{C}\)
2. \(20^\circ \mathrm{C}\)
3. \(28^\circ \mathrm{C}\)
4. \(36^\circ \mathrm{C}\)
Subtopic: Newton's Law of Cooling |
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The temperature of hot soup in a bowl goes \(98^{\circ}\) C to \(86^{\circ}\) C in \(2\) min. The temperature of the surrounding is \(22^{\circ}\) C. What is the time taken for the temperature of the soup to go from \(75^{\circ}\) C to \(69^{\circ}\) C?
(Assume Newton’s law of cooling is valid)
1. \(1\) min
2. \(1.4\) min
3. \(2\) min
4. \(3.2\) min
(Assume Newton’s law of cooling is valid)
1. \(1\) min
2. \(1.4\) min
3. \(2\) min
4. \(3.2\) min
Subtopic: Newton's Law of Cooling |
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An object cools down from \(80^\circ \text{C}\) to \(60^\circ \text{C}\) in \(5\) min in a surrounding of temperature \(20^\circ \text{C}.\) The time taken to cool from \(60^\circ \text{C}\) to \(40^\circ \text{C}\) will be:
(assume Newton's law of cooling to be valid)
(assume Newton's law of cooling to be valid)
| 1. | \({ 25 \over 3} ~\text {min}\) | 2. | \(5 ~\text {min}\) |
| 3. | \({ 25 \over 4} ~\text {min}\) | 4. | \(9~ \text {min}\) |
Subtopic: Newton's Law of Cooling |
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In an experiment to verify Newton’s Law of Cooling, a graph is plotted between the temperature difference \((\Delta T)\) of water and its surroundings and time, as shown in the figure. The initial temperature of the water is \(80^\circ\text C.\) What is the value of \(t_2 \text{?}\)
1. \(12\)
2. \(14\)
3. \(16\)
4. \(18\)
1. \(12\)
2. \(14\)
3. \(16\)
4. \(18\)
Subtopic: Newton's Law of Cooling |
Level 3: 35%-60%
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Read the following statements:
Choose the correct answer from the options given below:
| A. | When small temperature difference between a liquid and its surrounding is doubled the rate of loss of heat of the liquid becomes twice. |
| B. | Two bodies P and Q having equal surface areas are maintained at temperature 10ºC and 20 ºC. The thermal radiation emitted in a given time by P and Q are in the ratio 1 : 1.15 |
| C. | A car engine working between 100 K and 400 K has an efficiency of 75% |
| D. | When small temperature difference between a liquid and its surrounding is quadrupled, the rate of loss of heat of the liquid becomes twice. |
Choose the correct answer from the options given below:
| 1. | A, B, C only |
| 2. | A, B only |
| 3. | A, C only |
| 4. | B, C, D only |
Subtopic: Newton's Law of Cooling |
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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 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 metallic sphere cools from \(50^{\circ} \mathrm{C}\) to \(40^{\circ} \mathrm{C}\) in \(300~\text{s}\). If the atmospheric temperature around is \(20^{\circ} \mathrm{C}\), then sphere’s temperature after the next \(5\) minutes will be close to :
1. \( 33^{\circ} \mathrm{C} \)
2. \( 31^{\circ} \mathrm{C} \)
3. \( 35^{\circ} \mathrm{C} \)
4. \( 28^{\circ} \mathrm{C} \)
Subtopic: Newton's Law of Cooling |
75%
Level 2: 60%+
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