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.
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Answer:
minimum thickness of the coating = 122.868 nm
Explanation:
Given data
lens index of refraction = 1.29
wavelength = 634 nm
glass index of refraction = 1.53
to find out
minimum thickness of the coating
solution
we have given non reflective coating
so
we know that minimum thickness of the coating formula
minimum thickness of the coating = Wavelength / 4n
here n is coating index of refraction
so put here both value to get thickness
minimum thickness of the coating = Wavelength / 4n
minimum thickness of the coating = 634 / 4 ( 1.29 )
so minimum thickness of the coating = 122.868 nm
Wee can use here kinematics
as we know that

for shorter tree we know that


now since we know that other tree is twice high
So height of other tree is y = 39.2 m
now again by above equation



so the time taken is 2.83 s
Answer:
1keff=1k1+1k2
see further explanation
Explanation:for clarification
Show that the effective force constant of a series combination is given by 1keff=1k1+1k2. (Hint: For a given force, the total distance stretched by the equivalent single spring is the sum of the distances stretched by the springs in combination. Also, each spring must exert the same force. Do you see why?
From Hooke's law , we know that the force exerted on an elastic object is directly proportional to the extension provided that the elastic limit is not exceeded.
Now the spring is in series combination
F
e
F=ke
k=f/e.........*
where k is the force constant or the constant of proportionality
k=f/e
............................1
also for effective force constant
divide all through by extension
1) Total force is
Ft=F1+F2
Ft=k1e1+k2e2
F = k(e1+e2) 2)
Since force on the 2 springs is the same, so
k1e1=k2e2
e1=F/k1 and e2=F/k2,
and e1+e2=F/keq
Substituting e1 and e2, you get
1/keq=1/k1+1/k2
Hint: For a given force, the total distance stretched by the equivalent single spring is the sum of the distances stretched by the springs in combination.
<span>If you think about it, changing the scale to which something is measured does not affect the repeatability of the measurement. For instance, if you have a meter stick which was labeled incorrectly, that doesn't affect the fact that every measurement you take of a certain fixed distance will still be the same. Precision does not equal accuracy.</span>