The acceleration due to gravity on the planet A is 9 times the acceleration due to gravity on planet B. A man jumps to a height of 2 m on the surface of A. what is the height of jump by the same person on the planet B?

18 m

$g_{A}=9 g_{B}, \frac{g_{A}}{g_{B}}=9$

on planet A, In jumping the man goes up to height h_A = 2m

∴ PE gained by him is mg_A h_A

Same amount of work is done by jumping on planet B

∴ P.E. gained by him on planet mg_B h_B 

equating, mg_A h_A = mg_B h_B

g_A h_A = g_B h_B

$h_{B}=\frac{g_{A}}{g_{B}} h_{A}$ = 9 × 2 = 18 m

$\left[∵ \frac{g_A}{g_B}=9\right]$