⇦ | ⇨ |
A body takes 5 minute for cooling from 50⁰C to 40⁰C. Its temperature comes down to 33.33⁰C in next 5 minute. Temperature of surroundings is
Options
(a) 15⁰C
(b) 20⁰C
(c) 25⁰C
(d) 10⁰C
Correct Answer:
20⁰C
Explanation:
Apply Newton’s law of cooling
In first case, (50 – 40)/5 = K [(50+40)/2 – θ]
⇒ 2 = K [45 – θ] ——(i)
In second case, take 33.33 = 33 x (1/3) = 100/3
[40 – (100/3)]/5 = K {[40 + (100/3)/2] – θ}
⇒ 20/(5×3) = K [(110/3) – θ] ——(ii)
(i)/(ii) = (2 x 5 x 3)/20 = (45 – θ) / [(110/3) – θ]
⇒ 3/2 = (45 – θ) / [(110/3) – θ]
= 110 – 30 = 90 – 20 ⇒ θ = 20⁰C.
Related Questions: - In a parallel plate capacitor with plate area A and charge Q, the force on one plate
- Length of a conductor is 50 cm radius of cross section 0.1 cm and resistivity
- A uranium nucleus ₉₂ U ²³⁸ emits an α-particle and a β-particle in succession.
- Function of a rectifier is
- An α-particle and a proton are accelerated through same potential difference
Topics: Properties of Bulk Matter
(130)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- In a parallel plate capacitor with plate area A and charge Q, the force on one plate
- Length of a conductor is 50 cm radius of cross section 0.1 cm and resistivity
- A uranium nucleus ₉₂ U ²³⁸ emits an α-particle and a β-particle in succession.
- Function of a rectifier is
- An α-particle and a proton are accelerated through same potential difference
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