S*********g
发帖数: 5298 | 1 Assuming the density of rain drops is n, which is uniform and
time-independent, i.e.,
dn/dx=dn/dt=0.
Thus, the velocity in the rest frame is V1=Q/n
Now, let us solve this problem in the frame moving with the rain drops. In
this frame, the velocity of the wind shield is Vc=sqrt(v^2+V1^2) and the angle
between this velovity and the wind shield is (theta+phi) where
cos(theta)=a2/A sin(theta)=A1/A
and
cos(phi)=V1/Vc sin(phi)=v/Vc
During time period t, the number of the drops that hit on the win | g**i
发帖数: 5 | 2 Graphic method is straightfoward like following:
|\
|/\
|//\
| v*t |///\
|------\///\
\\\\\\\\///\
\\\\\\\\///\
\\\\\\\\///\
\\\\\\\\///\
\\\\\\\\///|
\\\\\\\\//|V1*t
\\\\\\\\/| |
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