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While driving north at 25m/s during a rainstorm you notice that the rain makes an angle of 38 degrees with the vertical. While driving back home moments later at the same speed but in the opposite direction, you see that the rain is falling straight down. From these observations, determine the angle of the raindrops relative to the ground.
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Let the velocity of rain w.r.t ground is given in vector notation as
Vx i + Vy j
Now Velocity of rain w.r.t driver moving north
( draw N-S and W-E normally then rotate counterclockwise by 90 degree. This is how i'm solving this problem)
V rain,driver_North= ( Vx - (-25) ) i + Vy j
V rain,driver_South= (Vx - 25 ) i + Vy j
You know that Vy/ Vx+ 25 = tan 38.......... (1)
also since while driving south the angle is 90 hence
Vy/ Vx-25 = tan 90 => Vx-25 =0 or Vx= 25m/s
From (1) you may calculate Vy = tan 38 * 2 * 25
So velocity of rain w.r.t ground has been found out to be
V rain,ground= 25 i + 50 * tan38 j
therefore
angle it makes is tan theta= 50 * tan38/25 => tan(theta)= 2*tan 38
v = 105 m/s a= 37 degrees vx = v * Cos(a) = 83.8567 m/s vy = v * Sin(a) = 63.1906 m/s tup = vy / 9.8 =6.448 s maximum height: h = 285 + Vy * tup + (1/2) * -9.8 * tup ^ 2 = 488.727 m tdown = Sqr(2 * h / 9.8)= 9.987 s a) T = tup + tdown = 16.435 s b) Range = Vx * T = 1378.19 m = 1.378 km c) vx =83.8567 i vyf = -9.8 * tdown = -97.8726 j m/s d) Vf = Sqr(vx ^ 2 + vyf ^ 2) = 128.884 m/s Angle = atan(vyf/vx) = 310.59 degrees e) 360-310.59 = 49.41 below horizontal f) height above cliff = h - 285 488.727-285 = 203.727 m g) vector magnitude 1.438 m/s Angle =14.236 degrees