Question

A metal ball suspended from the hook of a spring balance is kept immersed in a liquid other than water. On increasing the temperature of this liquid, the reading in the spring balance:

• A. increases
• B. decreases
• C. remains same
• D. may increases or decreases.

Answer 1

The correct option is A increases

${\gamma }_{metal}$ << ${\gamma }_{liquid}$
The upward thrust is $v_0{d}_{0}g$
When heated, the upward thrust is $v_t{d}_{t}g$
$v_t=v_0(1+{\gamma }_{metal}\Delta t)$
$d_t=d_0(1-{\gamma }_{liquid}\Delta t)$
$v_t\ast d_t=v_0\ast d_0(1-({\gamma }_{liquid}-{\gamma }_{metal}\left)\Delta t\right)$
Hence, the upward thrust will decrease when the liquid is heated.
$\therefore$ the reading of the balance will increase.