I think it’s the third law “for every action, there’s an equal and opposite reaction”
Explanation:
According to the law of conservation of energy,
......... (1)
As we know that, P.E = mgh
and, K.E = 
Therefore, putting these values of P.E and K.E into equation (1) as follows.

Now, initial case is that its starts with 50.3 m/s at bottom.
P.E = m and PE = 0
And, as it reaches the height h,
P.E = mgh
So, K.E will be m
Hence, speed = 6 m/s
One formula unit of sodium chloride contains an ionic bond. The sodium loses an electron to become positively charged, the chlorine atom accepts the electron to become negatively charged, and the two oppositely charged ions attract each other. This electrostatic force of attraction is called an ionic bond.
The answer to this question is "FIELD".
Electric "field" exists at a distance from two charged spheres. What happens is, we have two spheres either one is positively charging while the other one is negatively charged. When these spheres are placed in the same region, one sphere will tend to pull the negatively charged sphere and the two attracts each other. It is developing an electric field.
When a light wave strikes an object, it can be absorbed, reflected, or refracted by the object. All objects have a degree of reflection and absorption. ... In the natural world, light can also be transmitted by an object. That is, light can pass through an object with no effect (an x-ray, for example).