Question

Can anyone explain the logic behind this question?

Answer 1

C. `5.5 m/s`

Explanation:

This question is testing to see if you understand how projectile motion works. Instead of giving you a velocity and an angle, the problem has already broken the object's velocity down into `x` and `y` components. Your job is to correctly identify the velocity at the top of the object's path.

As far as the answer, look at it this way:

The only force acting on the object is gravity, so only the `y` (or vertical) velocity will change. Therefore, since there are no horizontal forces (thanks to negligible air resistance), the `x` velocity will always be the same as its original value (5.5 m/s).

At the top of the object's trajectory, it will be switching from going up to going down, so its vertical velocity is 0. That means the only velocity it has is its horizontal velocity.

Since the horizontal velocity is a constant 5.5 m/s, the velocity at the top of the object's path is also 5.5 m/s.

Final Answer