Answer:
[tex]VB - VA = - 33.4[/tex]
Explanation:
Generally the workdone in moving the proton is mathematically represented as
[tex]W = KE_f - KE_i[/tex]
Where [tex]KE_i \ and \ KE_f \ are\ the\ initial \ and \ final \ kinetic \ energy [/tex]
So
[tex]KE_i = \frac{1}{2} m v_a^2[/tex]
Here [tex]v_a[/tex] is the velocity at A with value 50 m/s
So
[tex]KE_i = \frac{1}{2} (1.67*10^{-27}) * 50^2 [/tex]
[tex]KE_i = 2.09 *10^{-24} \ J [/tex]
Also
[tex]KE_f = \frac{1}{2} m v_b^2[/tex]
Here [tex]v_a[/tex] is the velocity at A with value [tex]80 km/s = 80000 m/s [/tex]
=> [tex]KE_f = \frac{1}{2} (1.67*10^{-27}) * 80000^2 [/tex]
=> [tex]KE_f = 5.34 *10^{-18} \ J[/tex]
So
[tex]W = 5.34 *10^{-18} - 2.09 *10^{-24}[/tex]
[tex]W = 5.34 *10^{-18} m/s[/tex]
Now this workdone is also mathematically represented as
[tex]W = q * V[/tex]
So
[tex] q * V = 5.34 *10^{-18} [/tex]
Here [tex]q = 1.60*10^{-19} C[/tex]
So
[tex] V = \frac{5.34 *10^{-18} }{1.60*10^{-19}}[/tex]
[tex] V = 33.4 \ V [/tex]
Generally proton movement is in the direction of the electric field it means that [tex] VA>VB [/tex]
So
[tex]VB - VA = - 33.4[/tex]