Answer:
The best answer is of Keira's.
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.