9. You're an investigator for the National Transportation Safety Board, examining a subway accident in which a train going at 84km/hcollided with a slower train traveling in the same direction at 24km/h. Your job is to determine the relative speed of the collision, to help establish new crash standards. The faster train's "black box" shows that it began negatively accelerating at 1.9m/s^2when it was 46mfrom the slower train, while the slower train continued at constant speed.

a) What do you report?

Express your answer to two significant figures and include the appropriate units.

10. You and your roommate plot to drop water balloons on students entering your dorm. Your window is 10mmabove the sidewalk. You plan to place an X on the sidewalk to mark the spot a student must be when you drop the balloon. You note that most students approach the dorm at about 2m/s.

a) How far from the impact point do you place the X?

Express your answer to one significant figure and include the appropriate units.

14. A flock of geese is attempting to migrate due south, but the wind is blowing from the west at 4.7m/s.

a) If the birds can fly at 7.9m/srelative to the air, what direction should they head?

Express your answer using two significant figures.

18. In a chase scene, a movie stuntman runs horizontally off the flat roof of one building and lands on another roof 2.1mlower.

a) If the gap between the buildings is 4.9mwide, how fast must he run to cross the gap?

Express your answer to two significant figures and include the appropriate units.

19. A soccer player can kick the ball 26mmon level ground, with its initial velocity at 35to the horizontal.

a) At the same initial speed and angle to the horizontal, what horizontal distance can the player kick the ball on a 13upward slope?

Express your answer using two significant figures.

20. A diver leaves a 3-mboard on a trajectory that takes her 2.2mabove the board and then into the water 2.6mhorizontally from the end of the board.

a) At what speed did she leave the board?

Express your answer to two significant figures and include the appropriate units.

b) At what angle did she leave the board?

Express your answer using two significant figures.