How heavy is a 450 x 215 x 100 concrete block 3.5 newton?

Answer 1

(NOTE: As its presence has not been explained, I have assumed in the answer of this question that the '3.5 newtons' in the question represents the total weight of the object)

To answer this, we shall use the equation Force = Mass x Acceleration (F=MA)

Now, I assume when you say 'How heavy is....', you mean 'What is the mass of...'. Therefore, the equation should be rewritten so that the Mass can be obtained:

F=MA; Therefore M=F/A

We have the value for Force (3.5N), and the acceleration due to gravity (A) is generally accepted as being 9.8ms^-2 (to 2 significant figures, like the F value).

Therefore, by plugging them into the equation:

M = 3.5/9.8

Therefore the mass of the concrete block is 0.36kg (or 360g).