Neco Model Questions Vol1 2018 Physics Question 24

Practice objective / multiple choice question 24 from the 2018 Neco Model Questions Vol1 Physics examination.

Neco Model Questions Vol1 2018 Physics Objective / Multiple Choice Medium Difficulty
Question 24 NECO_MODEL_QUESTIONS_VOL1 • 2018 • PHYSICS • objective

A solid metal sphere of mass \(0.50\ \text{kg}\) and specific heat capacity \(c = 0.45\ \text{J g}^{-1}\!^{\circ}\text{C}^{-1}\) is initially at \(200^{\circ}\text{C}\) and is placed in a room where the ambient temperature is \(25^{\circ}\text{C}\). The sphere cools according to Newton's law of cooling, \(\displaystyle \frac{dT}{dt} = -k\,(T - T_{\text{room}})\). After \(5\) minutes its temperature has fallen to \(120^{\circ}\text{C}\). (i) Determine the cooling constant \(k\) (in \(\text{min}^{-1}\), to two decimal places). (ii) Predict the temperature of the sphere after \(15\) minutes (in \(^\circ\text{C}\), to the nearest degree).

Answer Options

A. k = 0.15 min^{-1}; T(15 min) ≈ 40 °C
B. k = 0.12 min^{-1}; T(15 min) ≈ 65 °C
Correct Answer C. k = 0.12 min^{-1}; T(15 min) ≈ 53 °C
D. k = 0.08 min^{-1}; T(15 min) ≈ 70 °C
Correct Answer
C
Correct Option:
k = 0.12 min^{-1}; T(15 min) ≈ 53 °C

About This Question

This is Neco Model Questions Vol1 2018 Physics Question 24. It is one of the objective questions from the 2018 Neco Model Questions Vol1 Physics examination.

Difficulty level: Medium .

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