Aball is rolling down a hill at +1.0 m/s, the ball is uniformly accelerating at
+4.9 m/s? , what will the ball's velocity be 4.0 s later?
+8.9 x 100° m/s
+2.0 x 10^1 m/s
+2.1 x 10^1 m/s
-1.9 x 10^1 m/s

2.1×10¹ m/s

Explanation:

Given:

v₀ = 1.0 m/s

a = 4.9 m/s²

t = 4.0 s

Find: v

v = at + v₀

v = (4.9 m/s²) (4.0 s) + (1.0 m/s)

v = 20.6 m/s

Rounded to two significant figures, the velocity is 21 m/s.

In scientific notation, the velocity is 2.1×10¹ m/s.

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .