Q. A cork is submerged in water by a spring attached to the bottom of a pail. When the pail is kept in a elevator moving with an acceleration downwards, the spring length
A) Increases
B) Decreases
C) Remains unchanged
D) Data insufficient
Explanation
(b) Density of cork $= d$, Density of water $= \rho$
Resultant upward force on cork $= V(\rho - d)g$
This causes elongation in the spring. When the lift moves down with acceleration $a$, the resultant upward force on cork $= V(\rho - d)(g - a)$ which is less than the previous value. So the elongation decreases
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.