"you and your physics major roomate become involved in a sinister plot to drop water balloons on students entering your dorm. Your room is 70 Feet above the sidewalk. You plan to place an X on the sidewalk to mark the spot a student must be when the balloon is dropped. The student will walk the distance from the X to the place the balloon hits in the time the balloon falls. After observing several students, you conclude most students walk at about 2.1 m/s when coming into the dorm."
How far from the impact point do you place the X?


How do I start this..

work out how high you're dropping the balloon from in meters.

Then use s=ut+\frac{1}{2}at^2 to work out the time it takes to drop.

then it should be trivial to find how far the victim has walked in that time.

You and your roommate plot to drop water balloons on students entering your dorm. Your window is 30 above 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. How far from the impact point do you place the X?

You and your roommate plot to drop water balloons on students entering your dorm. Your window is 30 above 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. How far from the impact point do you place the X? Express your answer to one significant figure and include the appropriate units