the relation that relates the speed of wave, frequency of wave and wavelength is given as
wavelength =
the speed of wave in a medium remains constant. hence the wavelength is inversely related to the frequency of wave.
that means, as the frequency is increased, the wavelength decreases and vice versa.
hence the correct choice is
B decreases
The final velocity is 1.37 m/s east
Explanation:
We can solve this problem by using the law of conservation of momentum: in fact, in absence of external forces, the total momentum of the two trains must be conserved before and after the collision.
So we can write:
where:
is the mass of the first train
is the initial velocity of the first train (we take east as positive direction)
is the mass of the second train
is the initial velocity of the second train
is the final combined velocity of the two trains
Re-arranging the equation and substituting the values, we find:
And the positive sign indicates their final direction is east.
Learn more about momentum here:
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