Problem: A particle is placed on the parabola at a point whose ordinate is 6. It is allowed to roll along the parabola until it reaches the nearest point whose ordinate is . The horizontal distance traveled by the particle (the numerical value of the difference in the abscissas of and ) is:
Answer Choices:
A.
B.
C.
D.
E.
Solution:
When
Because of symmetry the particle may roll from to or from to . In either case the horizontal distance is .