Consider two points in an electric field. The potential at point 1,
V
1
is 31 V.

The potential at point 2,
V
2
is 168 V. A proton is moved from point 1 to point 2.

a) Write an equation for the change of the electric potential energy
Δ
U of the proton, in terms of the symbol given and the charge of the proton e.

b) Solve for the numerical value of the change of the electric potential energy in electron volts (eV).

c) How much work is done by the electric force during the motion of the proton in J?

(a)

(b) 137 eV

(c)

Explanation:

Since electric field is conservative, the change in electric potential energy is simply the difference between the potential energy at position 2 and 1:

1 electron volt is defined as the energy required to move an electron (proton) and accelerating it through a potential difference of 1 volt.

The work done by the electric force in units of J is given by,

the tires are rotating at 0.434 rpmlinear speed=45 m/sdiameter=0.550 mradius=0.275 mnow v= rωω= v/rω=45/0.275ω=163.6 rad/sω=163.6 rad/s (1rev/2π rad) (60s/1m)ω=1563 rpm