⇦ | ⇨ |
Certain quantity of water cools from 70⁰ C to 60⁰C in the first 5 minutes and to 54⁰ C in the next 5 minutes. The temperature of the surroundings is
Options
(a) 45⁰ C
(b) 20⁰ C
(c) 42⁰ C
(d) 10⁰ C
Correct Answer:
45⁰ C
Explanation:
Let the temperature of surroundings be θ₀
By Newton’s law of cooling
(θ₁ – θ₂ / t) = k [(θ₁ – θ₂ / 2) – θ₀]
[(70 – 60) / 5] = k [(70 + 60 / 2) – θ₀] ⇒ 2 = k [65 – θ₀] ——(i)
Similarly, (60 – 54) / 5 = k = [(60 + 54 / 2) – θ₀]
6 / 5 = k [57 – θ₀] ——–(ii)
By dividing (i) by (ii) we have
10 / 6 = (65 – θ₀) / (57 – θ₀) ⇒ θ₀ = 45⁰
Related Questions: - Minimum and maximum values of Poisson’s ratio for a metal lies between
- A projectile is fired at 30°. Neglecting friction, the change in kinetic energy when
- Masses of three wires of copper are in the ratio of 1:3:5 and their lengths
- A wave travelling in the +ve x-direction having displacement along y-direction as 1m
- The radioactivity of a certain material drops to 1/16 of the initial value in 2 hours.
Topics: Properties of Bulk Matter
(130)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- Minimum and maximum values of Poisson’s ratio for a metal lies between
- A projectile is fired at 30°. Neglecting friction, the change in kinetic energy when
- Masses of three wires of copper are in the ratio of 1:3:5 and their lengths
- A wave travelling in the +ve x-direction having displacement along y-direction as 1m
- The radioactivity of a certain material drops to 1/16 of the initial value in 2 hours.
Topics: Properties of Bulk Matter (130)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
18000+ students are using NEETLab to improve their score. What about you?
Solve Previous Year MCQs, Mock Tests, Topicwise Practice Tests, Identify Weak Topics, Formula Flash cards and much more is available in NEETLab Android App to improve your NEET score.
Share this page with your friends
Leave a Reply