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.

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.