Question

Heisenberg’s uncertainty principle is not valid for:
(A) Moving electron
(B) Motor car
(C) Stationary particle
(D) All of these

Answer 1

Hint: The Heisenberg uncertainty principle is a very important principle of the quantum world. It states that the certainty in position and momentum of a microscopic particle cannot be measured simultaneously.

Complete answer:
We know that Heisenberg principle states that the position and momentum of a moving microscopic particle cannot be calculated simultaneously without significant error.
If we know the position of the particle with certainty then the momentum of the particle will have maximum uncertainty. In the same way if we know the momentum of the particle with certainty then the uncertainty in the position of the particle will be maximum.
The product of uncertainty in position and momentum is greater than or equal to ${\displaystyle \frac{h}{4\pi }}$
The mathematical expression for this principle is:
$$\mathrm{\Delta }x.\mathrm{\Delta }p\ge {\displaystyle \frac{h}{4\pi }}$$
From the statement of the principle it is clear that it is applicable to moving microscopic particles only.
So, we can measure the certainty in both position and momentum of a motor car. For a stationary particle the momentum is zero and the position can be measured with certainty.

Hence, the answer of the given question are options (B) and (C).

Note: The uncertainty principle is because of the wave nature of the particles. In large objects the wave nature is not much visible because of the very large mass of the object. So the uncertainty is much less in calculating position and momentum.