Answer:
In order to make this force twice as strong, F' = 2 F, the distance would have to be changed to half i.e. r' = r/2.
Explanation :
The electric force between two point charges is directly proportional to the product of charges and inversely proportional to the square of the distance between charges. It is given by :

r is the separation between charges


If F'= 2F

In order to make this force twice as strong, F' = 2 F, the distance would have to be changed to half i.e.
. Hence, this is the required solution.
Answer:
0.36
Explanation:
The maximum force of friction exerted by the surface is given by:
(1)
where
is the coefficient of friction
N is the normal reaction
The shed's weight is 2200 N. Since there is no motion along the vertical direction, the normal reaction is equal and opposite to the weight, so
N = 2200 N
The horizontal force that is pushing the shed is
F = 800 N
In order for it to keep moving, the force of friction (which acts horizontally in the opposite direction) must be not greater than this value. So the maximum force of friction must be

And substituting the values into eq.(1), we can find the maximum value of the coefficient of friction:

Pop rocks and soda..... baking soda and vinegar ...
Friction is used to refer to forces that resist relative motion, in general,whereas viscosity refers specifically to resistive forces that occur between layers of a fluid when fluids attempt to flow. Fluid friction is the force that resists the movement of a solid object through a fluid(liquid or gas). Sky divers falling down through the sky experience a type of fluid frictioncalled air resistance.