Question

Is velocity is zero at higest point in projectile motion?

Answer 1

If we throw any object other than verticle ( throwing upward direction in a straight line ) , it become projectile...

If we throw object in verticle direction , it moves in a straight line...after reaching the maximum height , it stops and move back the same path ( straight line )...Such motion is a type of 1 - D ( one - dimesional motion - having only one dimensiin - straight line motion) motion....
So verticle motion is not a projectile...

But if we thrown any object other than verticle , then it follow parabolic trajectory ( path ) or parabolic path...So such motions are projectile motion...

Note that : During projectile motion , Objects possess two velocities ( Horizontal motion and verticle motion )

If we throw any object at some angle , we make a components of velocity vector in two different directions ( Both are right angle to each other )
=> One component represent horizontal velocity
=> Other Component reperesnt verticle velocity

Important Note
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During projectile motion
=> Horizonatl motion is uniform
=> Verticle motion keeps on changing because og acceleration due to gravity...

At highest point , Verticle component of velocity is 0 and horizontal remain constant...

See snap...