Answer:
12.3 m/s
Step-by-step explanation:
m = mass of the box sliding on frictionless flat surface = 12.5 kg
x = compression of the spring = 14.1 cm = 0.141 m
k = spring constant = 94.5 kN/m = 94500 N/m
v = initial speed of the box
Using conservation of energy
Kinetic energy of the box = Spring potential energy
(0.5) m v² = (0.5) k x²
m v² = k x²
Inserting the values
(12.5) v² = (94500) (0.141)²
v = 12.3 m/s