This is also a bit fishy...

[Ferdinand]

Tom is a very large fellow, who is also a fishmonger. What does he weigh?

[NPK]

He weighs fish

[ski_power]

that was sooo funny...

 

he weighs fish.

 

How about this:

consider,

Mass of Tom=m

Mass of Earth=M

Newton's Gravitational constant=G

Acceleration due to gravity=g

Radius of Earth=R

 

We know,

F α Mm/R^2

F=GMm/R^2

GM=F(R^2)/m

 

where F/m=g

 

therefore,

GM=gR^2

 

Let Tom be at a height h from the surface of the earth,

 

GM=(g*)(R+h)^2

 

g*=Gravity at height h above earth's surface.

 

Therefore weight of Tom W,

W=(g*)(m)

 

Final answer W= (g*)(m)

 

 

Now considering Tom moving at a velocity v, where v is not neglible compared to the speed of light c.

 

We know m0= (I'm getting bored now, anybody care to complete it?)