Answer:
k = 773.64 N/m
Step-by-step explanation:
Given:
mass of the pellet, m = 3.56 x 10² kg
Compression in spring, x = 6.61 × 10⁻² m
Height of rise of the pellet, h = 4.83 m
Now, let k be the spring constant
From the concept of conservation of energy, we get
gravitation potential energy acquired by the pellet will be from the energy provided by the spring
thus,

where, g is the acceleration due to the gravity
on substituting the values, we get

or
1.685 = .002178 × k
k = 773.64 N/m