(a) 
The change in potential energy of the electron is given by:

where
is the magnitude of the electron's charge
is the magnitude of the electric field
d = 520 m is the distance through which the electron has moved
Substituting into the equation, we find

(b) 78 kV
The potential difference the electron has moved through is given by

where
is the magnitude of the electric field
d = 520 m is the distance through which the electron has moved
Substituting into the equation, we find

Answer:
Ans. B) 22 m/s (the closest to what I have which was 20.16 m/s)
Explanation:
Hi, well, first, we have to find the equations for both, the driver and the van. The first one is moving with constant acceleration (a=-2m/s^2) and the van has no acceletation. Let´s write down both formulas so we can solve this problem.


or by rearanging the drivers equation.

Now that we have this, let´s equal both equations so we can tell the moment in which both cars crashed.




To solve this equation we use the following formulas


Where a=1; b=-28.75; c=154
So we get:


At this point, both answers could seem possible, but let´s find the speed of the driver and see if one of them seems ilogic.
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This means that 21.63s will outcome into a negative speed, for that reason we will not use the value of 21.63s, we use 7.12s and if so, the speed of the driver when he/she hits the van is 20.16m/s, which is closer to answer A).
Best of luck
M = 40 Kg , g=9.8 m/s² , h = 2 m
PE = m g h
PE = (40) (9.8) (2)
PE = 784 J
KE = PE
½m v² = m g h
½ v² = g h
½ v² = (9.8) (2)
½ v² = 19.6
v² = 19.6×2
v² = 39.2
V = √39.2
V = 6.26 m/s
KE = ½mv²
KE = ½(40) (6.26)²
KE =783.8 J