Answer:
F= l x ( L - 1/2 g t²) g
Explanation:
Given that
length =L m
mass density = l kg/m
Distance cover by time t
y = 1/2 g t²
The remaining length of the pile = L - 1/2 g t²
So the total weight of the remaining length of the pile ,m
m= l x ( L - 1/2 g t²)
The force apply to the top of the rope to keep it motionless is F
F= m g
F= l x ( L - 1/2 g t²) g