Answer
acceleration due to gravity on Jupiter's moon,g' = 1.81 m/s²
weight of water melon on earth, W = 40 N
acceleration due to gravity on earth, g = 9.8 m/s²
a) Mass on the earth surface
M = 4.08 Kg
b) Mass on the surface of Lo
Mass of an object remain same.
Hence, mass of object at the surface of Lo = 4.08 Kg.
c) Weight at the surface of Lo
W' = m g'
W' =4.08 x 1.81
W' = 7.38 N
Vf = Vo + at
Vf = 20 m/s
Vo = 50 m/s
a = ?
t = 15
Therefore
20 = 50 + 15a
20 - 50 = 15a
-30 = 15a
a = -30 / 15
a = -2 m/s²
Answer and Explanation:
This experiment is known as Lenz's tube.
The Lenz tube is an experiment that shows how you can brake a magnetic dipole that goes down a tube that conducts electric current. The magnet, when falling, along with its magnetic field, will generate variations in the magnetic field flux within the tube. These variations create an emf induced according to Faraday's Law:

This emf induced on the surface of the tube generates a current within it according to Ohm's Law:

This emf and current oppose the flux change, therefore a field will be produced in such a direction that the magnet is repelled from below and is attracted from above. The magnitude of the flux at the bottom of the magnet increases from the point of view of the tube, and at the top it decreases. Therefore, two "magnets" are generated under and above the dipole, which repel it below and attract above. Finally, the dipole feels a force in the opposite direction to the direction of fall, therefore it falls with less speed.
It has to be one continuous column of cloud (air) connected to the ground and in constant rotation.