Two identical metal balls and

PHYSICS · Single correct · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter

Problem

Two identical metal balls

A

and

B

, each initially at

120^{\circ}\text{C}

, are placed in a room at

30^{\circ}\text{C}

. Ball

A

cools to

90^{\circ}\text{C}

3

minutes, while ball

B

cools to

90^{\circ}\text{C}

2

minutes. Which of the following correctly compares their cooling constants? (a)

k_B = \dfrac{4}{3}k_A

(b)

k_B = k_A

(c)

k_B = \dfrac{2}{3}k_A

(d)

k_B = \dfrac{3}{2}k_A