Many ways for example they look up related things and study them or they can test it and see what happens
Final speed = initial speed + (acceleration x time)
(final speed - initial speed) = acceleration x time
Time = (final speed - initial speed) / acceleration
-- Multiply each side of the formula by 2
-- Then divide each side by t
-- Then subtract V(i) from each side.
Explanation:
Use Pythagorean theorem:
r² = x² + y²
r² = (-6.46 m)² + (-3.78 m)²
r = 7.48 m