The initial force between the two charges is given by:

where k is the Coulomb's constant, q1 and q2 the two charges, d their separation. Let's analyze now the other situations:
1. F
In this case, q1 is halved, q2 is doubled, but the distance between the charges remains d.
So, we have:

So, the new force is:

So the force has not changed.
2. F/4
In this case, q1 and q2 are unchanged. The distance between the charges is doubled to 2d.
So, we have:

So, the new force is:

So the force has decreased by a factor 4.
3. 6F
In this case, q1 is doubled and q2 is tripled. The distance between the charges remains d.
So, we have:

So, the new force is:

So the force has increased by a factor 6.
Kinetic energy = mass time squared speed divided by 2
W=mv^2/2 = 50*10*10/2 = 2500 J
Answer:
(A) Total energy will be equal to 
(b) Energy density will be equal to 
Explanation:
We have given diameter of the plate d = 2 cm = 0.02 m
So area of the plate 
Distance between the plates d = 0.50 mm = 
Permitivity of free space 
Potential difference V =200 volt
Capacitance between the plate is equal to 
(a) Total energy stored in the capacitor is equal to


(b) Volume will be equal to
, here A is area and d is distance between plates

So energy density 
The elephant and the mouse having zero weight in a gravity free space will not bump into you at the same effect.
<u>Explanation:
</u>
When both are in a gravity free space, the weights are zero, as we know that the


But when they will acquire the speed of same magnitude, say v, their different masses will acquire different momentum, which will make the difference in effect while bumping.

And as we know
Therefore, effect of impact by elephant will be more than that of mouse
. An elephant breaking into you will take you back faster than a mouse in space hits you.