Four electrons are placed at the corner of a square
So we will first find the electrostatic potential at the center of the square
So here it is given as

here
r = distance of corner of the square from it center



now the net potential is given as


now potential energy of alpha particle at this position

Now at the mid point of one of the side
Electrostatic potential is given as

here we know that



now potential is given as


now final potential energy is given as

Now work done in this process is given as



Force , F = ma
F = m(v - u)/t
Where m = mass in kg, v= final velocity in m/s, u = initial velocity in m/s
t = time, Force is in Newton.
m= 1.2*10³ kg, u = 10 m/s, v = 20 m/s, t = 5s
F = 1.2*10³(20 - 10)/5
F = 2.4*10³ N = 2400 N
Answer:
H=1020.12m
Explanation:
From a balance of energy:
where H is the height it reached, d is the distance it traveled along the ramp and Ff = μk*N.
The relation between H and d is given by:
H = d*sin(30) Replace this into our previous equation:

From a sum of forces:
N -mg*cos(30) = 0 => N = mg*cos(30) Replacing this:
Now we can solve for d:
d = 2040.23m
Thus H = 1020.12m
Options:
A. The luminosity of Star 1 is a factor of 100 less than the luminosity of Star 2.
B. Star 1 is 100 times more distant than Star 2.
C. Without first knowing the distances to these stars, you cannot draw any conclusions about how their true luminosities compare to each other.
D. Star 1 is 10 times more distant than Star 2.
E. Star 1 is 100 times nearer than Star 2.
Answer:
D. Star 1 is 10 times more distant than star 2
Explanation:
For two stars of identical size and temperature, the closer one to us will appear brighter. The relationship between the distance and luminosity of stars is an inverse- square relationship.
Luminosity, L = 1/r²
Where r is the distance of the star to the earth
Since star 1 is dimmer in brightness than star 2 by a factor of 100,
L₁/L₂ = 1/100
i.e. L₁ = 1, L₂=100
L₁ = 1/r₁² ............(1)
1 = 1/r₁²
L₂ = 1/r₂²
100 = 1/r₂² .........(2)
divide equation (2) by equation (1)
100/1 = ( 1/r₂² )/ (1/r₁²)
100 = (r₁/r₂)²
r₁/r₂ = √100
r₁/r₂ = 10
r₁ = 10r₂
To answer the problem we would be using this formula which isE = hc/L where E is the energy, h is Planck's constant, c is the speed of light and L is the wavelength
L = hc/E = 4.136×10−15 eV·s (2.998x10^8 m/s)/10^4 eV
= 1.240x10^-10 m
= 1.240x10^-1 nm