Question

A proton and an electron traveling with the same velocity enter a uniform electric field. compared to the acceleration of the proton, the acceleration of the electron is

Answer 1

The acceleration of the electron is larger than the acceleration of the proton.

The reason for this is that the mass of the electron is smaller (about 1000 times smaller) than the mass of the proton. The two particles have same charge (e), so they experience the same force under the same electric field E:
$F=eE$ 
However, according to Newton's second law, the force is the product between the mass particle, m, and its acceleration, a:
$F=ma$ 
which can be rewritten as
$a= \frac{F}{m}$
we said that the force exerted on the two particles, F, is the same, while the mass of the electron is smaller: therefore, from the last formula we see that the acceleration of the electron will be larger than that of the proton.