Answer:
The answer is 0.83 seconds.
Explanation:
The formula of free fall is following:

Where g=9.8 m/s^2 and t=2 seconds, the rock takes:

19.6 meters. This is the half distance of the cliff. The whole distance is 39.2 meters. So it takes:

2.83 second to fall down completely. The rock takes the second half of the cliff in 0.83 seconds
Answer:
114.92749 keV
Explanation:
r = Radius of trajectory
m = Mass of electron = 
B = Magnetic field = 0.044 T
q = Charge of electron = 
The centripetal force and the magnetic forces are conserved

Velocity of first electron

Velocity of second electron

Total kinetic energy is given by

Converting to eV


The energy of incident electron is 114.92749 keV