Question

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?

Answer 1

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.