Answer:
The answer is <em>e.2</em>
Explanation:
We should make use of Snell's refractive law. The arriving wave has a certain velocity at T in a medium, then instantly it reaches a medium (same composition) at T' where velocity would either decrease or increase.
When the incidence angle is 30 °, and we want to make the refraction angle 90 ° such that no sound passes through the barrier (this would be named total internal refraction), so we want the second medium to be "faster" than in the first.
<em>The steps are in the image attached:</em>
Answer:
Option (C)
Explanation:
The nuclear energy is defined as a type of energy which liberates either by the process of nuclear fusion or nuclear fission and is mainly used to generate electricity. This energy is stored in the core of an atom (or nucleus).
It is highly effective, cost-effective and there is no emission of greenhouse gases.
But it also has some disadvantages, of which one is that it produces radioactive waste materials, which are difficult to dispose these substances and is also a very expensive method. These materials emit radiations that are harmful to the organisms. So, it is very challenging to dispose these radioactive waste materials.
Thus, the correct answer is option (C).
The initial kinetic energy of the car is
Then, the velocity of the car is decreased by half:
so, the new kinetic energy is
So, the new kinetic energy is 1/4 of the initial kinetic energy of the car. Numerically:
