Question

The direction of the oblique projectile becomes horizontal at the maximum height. What is the cause of it ?

Answer 1

If v is the velocity of projectile and θ is the angle it makes with the horizontal then there will be two components of velocity
vertical component-usinθ
horizontal component-ucosθ

At max. height, since θ becomes 0 and
sin 0=0 therefore there is no vertical component of velocity
therefore only horizontal component of velocity is there
thats why direction becomes horizontal at maximum height.

Answer 2

Hi

Here is your answer,

At the maximum height of projectile, the vertical component velocity because zero and only horizontal component velocity of projectile is there.

Hope it helps you !