That statement is flase. The index of refraction
of every material is more than 1.0 .
Answer:
16771720740.20324 J
Explanation:
= Density = 0.97 kg/m³
V = Volume = 
d = Diameter of cylinder = 230 m
r = Radius = 
h = Height of the cylinder = 640 m
v = Velocity of cylinder = 51 m/s
Mass of object is given by

Moment of inertia of a cylinder

Angular speed

Kinetic energy is given by

The kinetic energy contained by the tornado is 16771720740.20324 J
Hot coals of wood? Wood is not coals. So they can't burn their feet, there are no hot coals, just wood.
We Know, F = Gm₁m₂ / r²
When, distance is doubled, it would be:
F' = Gm₁m₂ / (2r)²
F' = Gm₁m₂ / 4r
So, we can see, Force has decreased by 4 times.
Hope this helps!
The answer is the last one