Newton's law of cooling

JEE Main Sample Questions › Thermal physics questions › Newton's law of cooling

A hot body placed in air is cooled down according to newton's law. The rate of decrease of temperature being K times the temperature difference from the surrounding. Starting from t=0, find the time in which the body will lose half the maximum temperature it can lose.
I got the answer as ln 2/K, but the answer given is ln2/3K

#Physics #Thermal physics

UP 0 DOWN 0 0 2
Post on FacebookPost anonymously?

2 Answers

24

eureka123 ·2009-10-05 00:56:00

it should be ln2/K

its just half life..[1]

UP 0 DOWN 0
Post on FacebookPost anonymously?

1

aposlil ·2009-10-05 01:01:34

Both of us are correct den. [1]

UP 0 DOWN 0
Post on FacebookPost anonymously?

Your Answer

Basic Integral Calculus Operators Symbols Matrix Cases

√ √ || {} [] () → ~ ^ x x x → → ln log lg lim lim cos sin tan cot arcsin arccos arctan

∫ ∫ ∫ ∫ ∫ ∬ ∬ ∬ ∬ ∬ ∭ ∭ ∭ ∭ ∭ ⨌ ⨌ ⨌ ⨌ ⨌

∑ ∑ ∑ ∑ ∑ ∮ ∮ ∮ ∮ ∮ ∏ ∏ ∏ ∏ ∏ ∐ ∐ ∐ ∐ ∐

+ - × ÷ ± ∓ = ∪ ∩ ≠ ∼ ≈ ∅ ∀ ∃ ∈ ∋ ∝ ≤ ≥ ≃ ≅ ≡ < > ≪ ≫ ⊂ ∉ ⊃ ⊆ ⊇ ⇒ ⇐ ⇔ ⇒ ⇐ ⇔ ⇑ ⇓ ⇕ → ← ↔ → ← ↔ ↑ ↓ ↕ ↖ ↗ ↘ ↙ ↪ ↩ ⇀ ↼ ⇁ ↽

° ∂ ∞ α β γ δ θ λ μ ν ξ π ρ σ φ ω ε ƒ κ τ υ Γ Δ Λ Σ Π Ω