Question

A candle of diameter $d$ is floating on a liquid in a cylindrical container of diameter $D(D>>d)$ as shown in figure. If it is burning at the rate of $2cm/hr$ then the top of the candle will

• A. Remain at the same height
• B. Fall at the rate of $1cm/hr$
• C. Fall at the rate of $2cm/hr$
• D. Go up at the rate of $1cm/hr$

Answer 1

Answer: (B)

Fall at the rate of $1cm/hr$

The candle floats on the water with half its length above and below water level. Let its length be $10cm$. with $5cm.$ below the surface and $5cm$, above it. If its length is reduced to $8cm$, It will have $4cm$. above water surface. So we see tip going down by I cm. So rate of fall of tip = $1cm/hr.$