A
photographer stands 44.5 m from
a rail road track, the
line of vision being perpendicular to the tracks.
A train passes at
|
Solution: Click For PDF Version As the photographer stands at a distance of 44.5 m from the railroad track, the image will be at the focal plane of the lens. Therefore, the image distance will be the focal length, which is 3.6 cm.
The line of
sight of the photographer is perpendicular to the train. Let the
shutter time for the exposure be
We use the result that the magnitude of the lateral magnification is given by
Therefore, D can be determined from the requirement that the size of the image is 0.75 mm. We find
As the train
is moving at
|
and the photographer takes a picture.
Using a camera with focal length
3.6 cm, we have to find the maximum exposure
time so that the blurring of the image on the film does not exceed
0.75 mm.
.
The train which is moving at
in
