At the highest point: kinetic energy is 0 due to the speed is 0
So the total mechanical energy is 20
Assume no frictions present, then the mechanical energy is conserved
So at the lowest point, kinetic energy = mechanical energy - potential energy
Answer will be 20 - 0.5 = 19.5 J
vf = vi + at
vf – vi = at<span>
<span>vi= 0, vf=26 and afor nil = 9.8m/s2</span></span>
26 = 9.8t
t =<span> 26 / 9.8 = 2.65 s
Now we know the total time, so we can calculate the time 1
second before it hit the ground.
<span>= 2.65 -1 = 1.65s
<span>Now again using the same equation, vf = vi+at, we can find vf
vi = 0, a = 9.8 t=1.65</span></span></span>
vf = 0 + 9.8(1.65) =
16.17 m/s<span>
</span><span>So,
the nail is traveling with the speed of 16.17m/s 1 second before it hits the
ground.</span>
Explanation:
We have,
Surface area, 
The current varies wrt time t as :
(a) At t = 2 seconds, electrical charge is given by :
(b) Current is given by :
Instantaneous current at t = 1 s is,
(c) Current is, 
Current density is given by electric current per unit area.
Therefore, it is the required explanation.
Scientists believe that light is made of streams of particles because light exhibits the particle nature. This can be explained on the basis of photoelectric effect observed when light is made to fall on the surface of a metal. when light falls on the surface of a metal, it makes the electron to eject out. This is possible only when light consists of small particle called photons. hence the scientists believe that light is made of streams of particles.
