Question

How does gravity affect projectile motion?

Answer 1

Gravity opposes the vertical component of velocity of the projectile with which it has been projected.

Now suppose a projectile is projected with an initial velocity `u` at an angle `theta` w.r.t the horizontal,so we can discuss the effect of gravity after breaking the velocity into two perpendicular components.

As gravity will affect the vertical component only.

So,vertical component of its velocity is `u sin theta`,so the projectile will keep on moving up,untill it's upward velocity becomes zero due to the downward direction of gravitational force acting on it.

So, at the highest point of its motion,the projectile has no vertical component of velocity,only horizontal component of velocity exists.

After that the projectile starts coming down being accelerated by gravity.So it's height decreases and at a time it reaches the ground.

So where,the horizontal component of velocity pushes it forwards,vertical component of velocity pushes it upwards,but it comes back to the ground just because of the gravitational force.