Wee can use here kinematics
as we know that

for shorter tree we know that


now since we know that other tree is twice high
So height of other tree is y = 39.2 m
now again by above equation



so the time taken is 2.83 s
Radiation fog is the fog that is formed when the heat absorbed the Earth's surface is released into the atmosphere producing fog. This only occurs when the air is clear and calm. In the center of an anticyclone, the conditions of the air are clear and calm which is favorable for the formation of radiation fog. The center of cyclones, on the other hand, is turbulent and cloudy which prevents the formation of radiation fogs.
Force = mass*acceleration so
3.6*2.5 =9 Newtons
D. frequency of the corresponding light wave