You are on the steep edge of the Grand Canyon, which is miles deep. You fire an arrow at an 89-degree angle towards the canyon (nearly straight up, with no hope of reaching the other side) Describe the arrow's trajectory, in particular noting approximately when the arrow has the most deceleration, the most acceleration, and then why the shift begins to happen. Cover all major points in the trajectory from initial shot to final resting place. When is the arrow moving fastest?

a. The arrow follows a parabolic path

b. As the arrow hits the ground,

Explanation:

a Describe the arrow's trajectory, in particular noting approximately when the arrow has the most deceleration, the most acceleration, and then why the shift begins to happen. Cover all major points in the trajectory from initial shot to final resting place.

This is because, the arrow is a projectile and its path follows a parabolic curve as it goes from initial shot to final resting place.

Its equation of motion is governed by y = ut - 1/2gt² where y = parabolic path, u = initial speed of arrow, t = time and g = acceleration due to gravity.

As the arrow rises, it undergoes the most deceleration. This is because as it rises, its speed decreases until it gets to the peak of its path, where its velocity is momentarily zero.  

Also, as the arrow drops, it undergoes the most acceleration. This is because as it drops from its peak, its speed increases until it gets to the bottom of its path, where its velocity is maximum and given by v = u' - gt where u' = velocity at peak = 0 m/s. So, v = 0 - gt = -gt.

b. When is the arrow moving fastest?

As the arrow hits the ground, its velocity is highest (maximum), so it is fastest at this point.

find the sum of the two horizontal vectors and the sum of the two vertical vectors

isoceles right angled triangle