Five friends built a marble tower. The marble tower had a curved track. The track was designed so that the marbles would move down the track in a circular path. The track ended on the floor. Each friend predicted how he or she thought the marble would move when it rolled off the end of the track onto the floor. This is what they said:

The best answer is of Keira's.

Step-by-step explanation:

The full question is as follows :

Given - Each friend predicted how he or she thought the marble would move when it rolled off the end of the track onto the floor.

This is what they said:

Magda : '' I think it will roll in circles.''

Soledad : '' I think it will curve for a bit and then straighten out.''

Allen : '' I think it will roll out in one big curve.''

Keira : '' I think it will roll in a straight line,''

Rafael : '' I think it will zigzag for a little while.''

To find - Which friend do you most agree with ?

Proof -

The best answer is Keira's.

The marble having the track will travel in a straight line.

The behavior is true for all objects.

If no outside force act on an object, the object will travel in a straight line at a constant speed.

When the marble leaves the end of the track, it is no longer in contact with the walls of the track.

That is , the marble has no longer a center-pushing force.

According to Newton's First law, an object remains at rest or in uniform motion in a straight line unless acted upon by an external force.

Since, there is no longer a center-pushing force so the marble rolls off the end of the track in a straight line path across the floor.