Answer:

Explanation:
the slits spacing, d = 0.21 mm
distance of screen, D = 61 cm
The condition for minima is given as

So, first minima, n = 0

fifth minima, n = 4


For small angle

From the figure:





Here easy answer from online
In scientific contexts, mass is the amount of "matter" in an object (though "matter" may be difficult to define), whereas weight is the force exerted on an object by gravity.
Answer: The theory might have become Obsolete or Superseded
Explanation:
A theory becomes obsolete or superseded if it becomes inadequate, false or incomplete in how its describes reality. It does not matter if it was once accepted. There are some theories such as Lysenkoism that are currently described as being obsolete because it does not conform to current reality. Another example of a theory that was superseded is the phlogiston theory. It was replaced a different theory of energy.
Displacement depends upon the path taken as it is a vector.
From your problem above we would have a total displacement of;
Defining +x direction as east and -x direction as west
6east-3west+1east+6east-7west
6-3+1+6-7=3 blocks east or + x-direction
So even though they walked a total of 17 blocks it ends up only being 3 blocks total in +xdirection that was travelled by displacement.
Any questions please ask.