Answer:



Given:
Weight of solid in air, 
Weight of solid in water, 
Weight of solid in liquid, 
Solution:
Calculation of:
1. Relative density of solid, 


2. Relative density of liquid, 


3. Density of liquid in S.I units:
Also, we know:

where
= density of liquid
= density of water
Now, from the above formula:


Height of the waterfall is 0.449 m
its horizontal distance will be 2.1 m
now let say his speed is v with which he jumped out so here the two components of his velocity will be


here the acceleration due to gravity is 9.81 m/s^2 downwards
now we can find the time to reach the other end by y direction displacement equation


also from x direction we can say


now we have

we will plug in this value into first equation



now as we know that

t = 0.63 s


so his minimum speed of jump is 4.1 m/s
There are not enough electrons in atoms to affect the total mass, so the total mass is just the weight of the protons and neutrons.