Answer: 
Explanation:
Given
Cross-sectional area 
Dielectric constant 
Dielectric strength 
Distance between capacitors 
Maximum charge that can be stored before dielectric breakdown is given by
![\Rightarrow Q=CV\\\\\Rightarrow Q=\dfrac{k\epsilon_oA}{d}\cdot (Ed)\quad\quad [V=E\cdot d]\\\\\Rightarrow Q=k\epsilon_oAE\\\\\Rightarrow Q=4\times 8.85\times 10^{-12}\times 0.4\times 10^{-4}\times 2\times 10^8\\\\\Rightarrow Q=28.32\times 10^{-8}\\\\\Rightarrow Q=283.2\times 10^{-9}\ nC](https://tex.z-dn.net/?f=%5CRightarrow%20Q%3DCV%5C%5C%5C%5C%5CRightarrow%20Q%3D%5Cdfrac%7Bk%5Cepsilon_oA%7D%7Bd%7D%5Ccdot%20%28Ed%29%5Cquad%5Cquad%20%5BV%3DE%5Ccdot%20d%5D%5C%5C%5C%5C%5CRightarrow%20Q%3Dk%5Cepsilon_oAE%5C%5C%5C%5C%5CRightarrow%20Q%3D4%5Ctimes%208.85%5Ctimes%2010%5E%7B-12%7D%5Ctimes%200.4%5Ctimes%2010%5E%7B-4%7D%5Ctimes%202%5Ctimes%2010%5E8%5C%5C%5C%5C%5CRightarrow%20Q%3D28.32%5Ctimes%2010%5E%7B-8%7D%5C%5C%5C%5C%5CRightarrow%20Q%3D283.2%5Ctimes%2010%5E%7B-9%7D%5C%20nC)
Answer:
Eleven seconds.
Explanation:
Two keys are needed to solve this problem. First, the conservation of momentum: allowing you to calculate the cart's speed after the elephant jumped onto it. It holds that:

So, once loaded with an elephant, the cart was moving with a speed of 4.29m/s.
The second key is the kinematic equation for accelerated motion. There is one force acting on the cart, namely friction. The friction acts in the opposite direction to the horizontal direction of the velocity v0, its magnitude and the corresponding deceleration are:

The kinematic equation describing the decelerated motion is:

It takes 11 seconds for the comical elephant-cart system to come to a halt.