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Newton's law of cooling: time taken to cool through a second temperature interval

The same question, asked 6 times: May 2021 S1*, 9 May 2023 S2*, 21 Apr 2025 S2*, 25 Apr 2025 S1*, 11 Apr 2026 S2*, 16 Apr 2026 S2. Every wording below, oldest first.

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  1. Question 1

    May 2021 S1

    39
    The temperature of a liquid drops from 365 K to 361 K in 2 min. Find the time during which temperature of the liquid drops from 344 K to 342 K. (Take, room temperature = 293 K)

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  2. Question 2

    9 May 2023 S2

    40
    The temperature of a liquid falls from 365 K to 359 K in 3 minutes. The time during which temperature of this liquid falls from 342 K to 338 K is [Let the room temperature be 296 K]

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  3. Question 3

    21 Apr 2025 S2

    20
    Hot water cools from 80∘C80^{\circ}C to 60∘C60^{\circ}C in 1 minutes. In cooling from 60∘C60^{\circ}C to 50∘C50^{\circ}C it will take (room temperature =30∘C=30^{\circ}C )

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  4. Question 4

    25 Apr 2025 S1

    26
    A body cools from 80∘C80^{\circ}C to 50∘C50^{\circ}C in 5 min. In the next time of ' tt ' in, the body continues to cool from 50∘C50^{\circ}C to 30∘C30^{\circ}C. The total time taken by the body to cool from 80∘C80^{\circ}C to 30∘C30^{\circ}C is [The temperature of the surroundings is 20∘C20^{\circ}C.]

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  5. Question 5

    11 Apr 2026 S2

    112
    A body cools in 77 minutes from 60∘60^\circC to 40∘40^\circC. What time (in minutes) does it take to cool from 40∘40^\circC to 28∘28^\circC, if its surrounding temperature is 10∘10^\circC ? (Newton's law of cooling holds good)

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  6. Question 6

    16 Apr 2026 S2

    112
    A bowl filled with very hot water cools from 98∘C98^\circ\mathrm{C} to 86∘C86^\circ\mathrm{C} in 2 minutes when the room temperature is 22∘C22^\circ\mathrm{C}. How long it will take to cool from 75∘C75^\circ\mathrm{C} to 69∘C69^\circ\mathrm{C} ?

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