physics
posted by Anonymous on .
From inside your apartment, you watch rain fall straight down at a constant speed of 9 m/s. Your friend L calls you as she is driving toawards the west at a constant of 90 km/hr. What with what velocity does L see the rain fall as she looks out her driver's side window?
I know I'm trying to find the velocity relative to L driving. I just don't know where to start. How would the velocity of the rain change?

Be sure to take care of units conversions.
From L's point of reference, the rain has the x component from her driving plus the y component of the rain falling. Find the resultant vector. 
The velocity of the rain with respect to someone in the car is the vector sum of the downward rain velocity (9 m/s) and the car's speed, 90000m/3600 s = 25 m/s. Use the Pythagorean theorem for the resultant