- 1(current)
Q. No.The temperature of a body falls from \(50^{\circ}\mathrm{C}\) to \(40^{\circ}\mathrm{C}\) in 10 minutes. If the temperature of the surroundings is \(20^{\circ}\mathrm{C}\)hen the temperature of the body after another 10 minutes will be:
1. \(36.6^{\circ}\mathrm{C}\)
2. \(33.3^{\circ}\mathrm{C}\)
3. \(35^{\circ}\mathrm{C}\)
4. \(30^{\circ}\mathrm{C}\)
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A pan filled with hot food cools in 2 minutes from \(94^{\circ}\mathrm{C}\) to \(86^{\circ}\mathrm{C}\) when the room temperature is \(20^{\circ}\mathrm{C}\). How long will it take to cool from \(71^{\circ}\mathrm{C}\) to \(69^{\circ}\mathrm{C}\)?
| 1. | 50 sec | 2. | 52 sec |
| 3. | 42 sec | 4. | 48 sec |
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A block of metal is heated to a temperature much higher than the room temperature and allowed to cool in a room free from air currents. Which of the following curves correctly represents the rate of cooling?
| 1. |  |
2. |  |
| 3. |  |
4. |  |
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A certain quantity of water cools from \(70^{\circ}\mathrm{C}\) to \(60^{\circ}\mathrm{C}\) in the first 5 minutes and to \(54^{\circ}\mathrm{C}\) in the next 5 minutes.
The temperature of the surroundings will be:
| 1. | \(45^{\circ}\mathrm{C}\) | 2. | \(20^{\circ}\mathrm{C}\) |
| 3. | \(42^{\circ}\mathrm{C}\) | 4. | \(10^{\circ}\mathrm{C}\) |
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Hot coffee in a mug cools from \(90^{\circ}\mathrm{C}\) to \(70^{\circ}\mathrm{C}\) in 4.8 minutes. The room temperature is \(20^{\circ}\mathrm{C}\). Applying Newton's law of cooling, the time needed to cool it further by \(10^{\circ}\mathrm{C}\) should be nearly:
| 1. | 4.2 minute | 2. | 3.8 minute |
| 3. | 3.2 minute | 4. | 2.4 minute |
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A body cools from a temperature of \(3T\) to \(2T\) in \(10\) minutes. The room temperature is \(T\). Assuming that Newton's law of cooling is applicable, the temperature of the body at the end of the next \(10\) minutes will be:
| 1. | \(\frac{7}{4}T\) | 2. | \(\frac{3}{2}T\) |
| 3. | \(\frac{4}{3}T\) | 4. | \(T\) |
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Consider two hot bodies, and which have temperatures of \(100^{\circ}\mathrm{C}\) and \(80^{\circ}\mathrm{C}\) respectively at t=0. The temperature of the surroundings is \(40^{\circ}\mathrm{C}\). The ratio of the respective rates of cooling and of these two bodies at t = 0 will be:
1.
2.
3.
4.
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A body cools down from \(80^{\circ}\mathrm{C}\) \(70^{\circ}\mathrm{C}\)
| 1. | less than 5 minutes. |
| 2. | equal to 5 minutes. |
| 3. | more than 5 minutes. |
| 4. | can't say anything as the temperature of the surroundings is not known. |
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- 1(current)
Q. No.
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