The dummy is moving with a speed 0 km/h relative to the seat in which it is sitting.
If the relative speed was non-zero, the dummy would move away from its seat, which contradicts the problem formulation.
webpage of a scientist who is trying to sell a new invention
trying to dell = vested interest.
umiversity should be objective impartial
Answer:
The length of the tube is 3.92 m.
Explanation:
Given that,
Electric potential = 100 MV
Length = 4 m
Energy = 100 MeV
We need to calculate the value of 
Using formula of relativistic energy

Put the value into the formula


Here, 



We need to calculate the length
Using formula of length

Put the value into the formula


Hence, The length of the tube is 3.92 m.