Final answer:
In a vacuum tube, electrons can travel at high speeds, determined by the voltage applied. The maximum speed of non-relativistic electrons in this scenario is approximately 6.6x10^6 m/s.
Step-by-step explanation:
In a vacuum tube, electrons can travel at high speeds. However, the speed at which electrons travel is not affected by the absence of air. It is determined by the voltage applied to accelerate the electrons. The maximum speed that non-relativistic electrons can reach in an evacuated tube can be calculated using the classical equation:
v = sqrt((2*e*V)/m)
Where v is the speed of the electron, e is the charge of the electron, V is the accelerating voltage, and m is the mass of the electron. In this case, the electrons are accelerated with a voltage of 40 kV. Plugging the given values into the equation, we get:
v = sqrt((2*1.6x10^-19 C * 40,000 V)/(9.11x10^-31 kg))
v ≈ 6.6x10^6 m/s
Therefore, the maximum speed of electrons in this scenario is approximately 6.6x10^6 m/s.