An arrow is fired directly upwards at 15m/s from the ground level. a: how long is the arrow in the air? b: how high does the arrow go? c: how fast is it going just before it strikes the ground?

Given that,

Initial Velocity, Vi = 15 m/s

acceleration due to gravity , g = 9.81 m/s²

Time in air, t = ?

Height, h = ?

Speed before striking ground, Vf = ?

Since, we know that,

2as = Vf² - Vi²

2*(-9.81)*s = 0 - 15²

solving above equation we have,

s= 11.46 m

or

h= 11.46 m

Height achieve by arrow will be 11.46 m

Since,

s = Vt

t= s/ V

t = 11.46/ 15

t = 0.76

Total time in air = 2 * t = 2*0.76

Time in air will be 1.53 s

Since,

2as = Vf² - Vi²

2*9.81* 11.46 = Vf² - 0

solving above equation we have,

Vf = 14.99 m/s

or

Velocity of arrow just before striking ground will be 15 m/s approximately.

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 .