Answer:

Explanation:
Mass of a proton, 
Mass of an electron, 
The distance between the electron and the proton is, 
We need to find the mutual attractive gravitational force between the electron and proton. The gravitational force is given by :

Where G is the universal Gravitational constant

So, the force between the electron and proton is
.
Answer:
The energy required to accelerate an electron is 0.582 Mev and 0.350 Mev.
Explanation:
We know that,
Mass of electron 
Rest mass energy for electron = 0.511 Mev
(a). The energy required to accelerate an electron from 0.500c to 0.900c Mev
Using formula of rest,



(b). The energy required to accelerate an electron from 0.900c to 0.942c Mev
Using formula of rest,



Hence, The energy required to accelerate an electron is 0.582 Mev and 0.350 Mev.
Explanation:
Given that,
Bill is riding his bicycle at 5 m/s eastward: and Carlos is driving his car at 15 m/s westward.
Taking eastward as positive direction, we have:
is the velocity of Bill with respect to Amy (which is stationary)
is the velocity of Carlos with respect to Amy.
Bill is moving 5 m/s eastward compared to Amy at rest, so the velocity of Bill's reference frame is

Therefore, Carlos velocity in Bill's reference frame will be

So, the magnitude is 20 m/s and the direction is westward (negative sign).