Answer:
[tex]\huge\boxed{\sf s = 320}[/tex]
Step-by-step explanation:
Given that,
[tex]s \propto t^2[/tex]
Converting proportionality into equality and adding a constant.
s = kt² ----------------(1)
Given that, s = 80 when t = 4
Put in Eq. (1)
80 = k(4)²
80 = k(16)
Divide 16 to both sides
80/16 = k
5 = k
Now,
Put t = 8 in Eq. (1)
s = (5)(8)²
s = (5)(64)
[tex]\rule[225]{225}{2}[/tex]