At the uppermost point of a projectile its velocity and acceleration are at what angle with each other?

Acceleration of a body is given by a = 2sqrt(t) , where t is the time. If the body starts from rest what will be its velocity and acceleration 4 s later ? [ SI units are to be used ]

What is a projectile .Show that the path following by a projectile is a parabolic , when it is projected at an angle theta with the horizontal. Obtain an expression for maximum height.

What is a projectile .Show that the path following by a projectile is a parabolic when it is projected at an angle theta with the horizontal. Obtain an expression for time of flight.

What is a projectile .Show that the path following by a projectile is a parabolic when it is projected at an angle theta with the horizontal. Obtain an expression for Horizontal range.

Define angular acceleration. What is its unit?

Can the directions of velocity and acceleration be opposite to each other? Explain with examples. Or,Can the velocity of a particle be towards east but its acceleration towards west?

Two bodies are moving such that the velocity of one is twice that of the other and they make an angle of 60^@ with each other. Find the relative velocity of one with respect to the other.