After a weight was suspended from a 12 cm long spring, its length became 15 cm

After a weight was suspended from a 12 cm long spring, its length became 15 cm. Find the weight of the weight if the coefficient of spring stiffness is 900 N / m.

Initial data: l (length of an undeformed spring) = 12 cm; l1 (length of the deformed spring) = 15 cm; k (coefficient of spring stiffness) = 900 N / m.

Constants: g (acceleration due to gravity) = 10 m / s ^ 2.

SI system: l = 12 cm = 0.12 m; l1 = 15 cm = 0.15 m.

1) Spring deformation: Δl = l1 – l = 0.15 – 0.12 = 0.03 m.

2) The force that acts on the spring: Fcont. = Ft = k * Δl = 900 * 0.03 = 27 N.

3) We calculate the mass of the cargo: Ft = m * g and m = Ft / g = 27/10 = 2.7 kg.

Answer: The weight of the cargo is 2.7 kg.