To solve this problem we will consider the definition of Minimum Energy, as the change between the minimum voltage and its distance. Mathematically it can be written as
Rearranging to find the Voltage,
Replacing,
Therefore the minimum voltage needed between your finger and the doorknob to generate this spark is 28.5kV
<span>If "m" balls are thrown per second, the time taken for a ball to reach its maximum height will be 1/m seconds. How to get this? See that the next ball is thrown only when the previous ball reaches its maximum height. If 'm' balls were thrown in 1 second this means that each ball was attaining its maximum ht in 1/m seconds.
This was the main part. Now we can proceed to find maximum height in 2 ways-
a)
We know for upward journey ,
t=1/m
a=-g
v=u-gt
final velocity ,v = 0 (at highest point)
u
=gt = g/m
Now we can apply
h=ut-1/2 gt^2
Putting the values of u,t, we will get
h= g/2m^2
b)
The second method uses a trick that time taken to reach the maximum ht is same as time taken to fall down.
So, we will now consider the downward journey of ball which also takes 1/m seconds
We apply
h=ut+1/2gt^2
Here u=0 ,t=1/m
We will again get ,
h=g/2m^2</span>
Yes bc math, numbers and more
