Question

Two stones each of mass 5kg fall on a wheel from a height of 10m. The wheel stirs 2kg water. The rise in temperature of water would be

• A. 2.6⁰ C
• B. 1.2⁰ C
• C. 0.32⁰ C
• D. 0.12⁰ C

Answer 1

Answer: (D)

0.12⁰ C

Answer 2

For the given condition potential energy of the two masses will convert into heat and temperature of water will increase W = JQ ⇒ 2m × g × h = J(m_w S ∆t)

⇒ $2 \times 5 \times 10 \times 10 = 4.2(2 \times 10^{3} \times \Delta t)$

∴ $\Delta t = \frac{1000}{8.4 \times 10^{3}} = 0.119^{o}C = 0.12^{o}C$.