A falling stone takes Δt = 0.31 s to travel past a window 2.2 m tall. From what height above the top of the window did the stone fall?

1 Answer

• To solve this you have to assume that the stone was dropped from rest since no

  other info was given, I’ll assume that.

  y = yo + Vot + gt^2/2

  2.2 = 0 + 0.31Vo + (9.8*0.31^2)/2 = 0.31Vo + 0.47

  Solve for the initial velocity Vo of the stone at the top of the window:

  Vo = (2.2-0.47)/0.31 = 5.6 m/s

  To solve for the distance above window use: Vf^2 = Vi^2 + 2gd

  d = (Vf^2-Vi^2)/2g = (5.6^2-0^2)/19.6 = 1.6 m

  —> 1.6 m above the top of the window