A calorimeter of mass 0.2 kg and specific heat 900 J / kg - K. Containing 0.5 kg of a liquid of specific heat 2400 J / kg - K. Its temperature falls from 60° C to 55° C in one minute. Find the rate of cooling.

Question

A calorimeter of mass 0.2 kg and specific heat 900 J / kg - K. Containing 0.5 kg of a liquid of specific heat 2400 J / kg - K. Its temperature falls from 60° C to 55° C in one minute. Find the rate of cooling. (A) 5 J/s (B) 15 J/s (C) 100 J/s (D) 115 J/s

Tardigrade Admin · Accepted Answer

Rate of cooling (here it is rate of loss of heat) (d Q/d t) =(m c +W) (d θ/d t) =(ml cl+mc cc) (d θ/d t) ⇒ (d Q/d t) =(0.5 × 2400+0.2 × 900)((60-55/60)) =115 ( J / sec)

Q. A calorimeter of mass $0.2 k g$ and specific heat $900 J / k g - K$ . Containing $0.5 k g$ of a liquid of specific heat $2400 J / k g - K$ . Its temperature falls from $6 0^{\circ} C$ to $5 5^{\circ} C$ in one minute. Find the rate of cooling.

5 J/s

15 J/s

100 J/s

115 J/s

Rate of cooling (here it is rate of loss of heat)
$\frac{d Q}{d t} = (m c + W) \frac{d θ}{d t}$
$= (m_{l} c_{l} + m_{c} c_{c}) \frac{d θ}{d t}$
$\Rightarrow \frac{d Q}{d t} = (0.5 \times 2400 + 0.2 \times 900) (\frac{60 - 55}{60})$
$= 115 \frac{J}{s e c}$

Q. A calorimeter of mass 0.2kg and specific heat 900J/kg−K. Containing 0.5kg of a liquid of specific heat 2400J/kg−K. Its temperature falls from 60∘C to 55∘C in one minute. Find the rate of cooling.