Is the acceleration of a projectile equal to zero when it reaches the top of its trajectory?if not,why not?

Question

Is the acceleration of a projectile equal to zero when it reaches the top of its trajectory?if not,why not?

Answer 1

if the acceleration were 0 at the top, it would just float in mid air...

Answer 2

The velocity is still changing, even at the top of the trajectory.

Changing velocity --> acceleration is not zero.

Answer 3

Final Velocity = Initial Velocity + Acceleration * Change in Time

vf = vi + a Δt

the final vertical velocity is 0, because initial vertical velocity and acceleration over time are equal.  (acceleration being negative)

So, vertical velocity is 0, but acceleration of gravity stays constant at 9.8 m/s/s down.

BTW: the projectile is still moving horizontally at the top of a trajectory, so all velocity is not 0.  Just vertical velocity.

Answer 4

no, acceleration is constant, downward at 9.8 m/s²

Why not? because gravity is a constant force, which results in a constant acceleration, by F = ma

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