This is in basic contrast to the situation of ‘free
fall under gravity’ where the time of fall is independent of the mass of
the body Note that in this example we have ignored the acceleration
due to gravity in calculating the time of fall To see if this is justified,
let us calculate the acceleration of the proton in the given electric
field:
p
p
e E
a
m
=
     
19
4
1
27
(1 6
10
C)
(2 0
10
N C
)
1 67
10
kg −
−
−
×
×
×
=
×
     
12
–2
1 9
10
m s