Explanation:
We have,
Speed of plane a is 900 km/h
Plane b is moving at a rate of 
It is required to find which plane is faster. To find which plane is faster, we need to compare their speeds.
Speed of a plane a is 900 km/h and that of plane b is 50 km/h. So, we can say that plane a is moving faster.
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Acceleration = v-u/t
= (45-30)/15
= 1 km/h
Distance = ut + 1/2 at^2
s = [30 x 15] + 1/2 x 1 x 15^2
= 562.5 km
Hope this helps
It produces only virtual images is the answer