A vertically rising body has speeds u/2, u/3 and u/4 at successive points A, B, C. If AB/BC=20/x, find x.
Physics · Mixed Chapter
JEE Main Practice

Question

A vertically rising body has speeds u/2, u/3 and u/4 at successive points A, B, C. If AB/BC=20/x, find x.

G1 Physics · Accepted Answer

Step 1: Relative height difference between two speed levels is Δh=(v₁²−v₂²)/(2g). Step 2: AB=[u²/4−u²/9]/(2g)=5u²/(72g). Step 3: BC=[u²/9−u²/16]/(2g)=7u²/(288g). Step 4: AB/BC=20/7, so x=7.