Newton’s second law gives us the relationship of force F, mass m and acceleration a. The formula is given as:
F = m a --> 1
However we also know that the relationship of mass m, density ρ, and volume V is:
m = V ρ --> 2
Therefore substituting equation 2 to equation 1:
F = ρ V a = ρ V g
where a is acceleration due to gravity, ρ is density of water and V is the volume of the casting, therefore:
F = (1x10^-3 kg/cm^3) (4840 cm^3) (9.8 m/s^2)
F = 47.432 kg m/s^2
F = 47.432 N
Going back to equation 1:
47.432 N = m (9.8 m/s^2)
m = 4.84 kg
Hence the weight of the final casting is 4.84 kg
