The trains take <u>57.4 s</u> to pass each other.
Two trains A and B move towards each other. Let A move along the positive x axis and B along the negative x axis.
therefore,

The relative velocity of the train A with respect to B is given by,

If the train B is assumed to be at rest, the train A would appear to move towards it with a speed of 170 km/h.
The trains are a distance d = 2.71 km apart.
Since speed is the distance traveled per unit time, the time taken by the trains to cross each other is given by,

Substitute 2.71 km for d and 170 km/h for 

Express the time in seconds.

Thus, the trains cross each other in <u>57.4 s</u>.
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Explanation:
The given data is as follows.


Electric potential energy (
) = ?
Formula to calculate electric potential energy is as follows.
= 
= 
Thus, we can conclude that the electric potential energy of the pair of charges when the second charge is at point b is
.
Answer: Option (b) is the correct answer.
Explanation:
A gamma particle is basically a photon of electromagnetic radiation with a short wavelength.
Symbol of a gamma particle is
. Hence, charge on a gamma particle is also 0.
For example, 
So, when a nucleus decays by gamma decay to a daughter nucleus then there will occur no change in the number of protons and neutrons of the parent atom but there will be loss of energy as a nuclear reaction has occurred.
Thus, we can conclude that the statement daughter nucleus has the same number of nucleons as the original nucleus., is correct about if a nucleus decays by gamma decay to a daughter nucleus.
Answer:
An X-ray is used to take pictures of your bones. The waves that are used are known as radiation waves.