Answer:
D) Vertically.
Explanation:
A free body diagram is used to represent all the forces acting in a body. forces like, the force of gravity as a result of the gravitational interaction between the object and the Earth (W), the frictional force opposite to the movement of the object (
), the normal force due to the plane and the object (N) and the force applied to start the movement in a particular direction (F).
As is show in the free body diagram of the system, W, which is the weight of the body as a consequence of the gravitational force, is at an angle
below the inclined plane. that angle between the plane and the x axis is the same that the one of the inclined plane with respect to the horizontal, Since its sides are perpendicular.
Notice how W goes always in the direction to the center of mass of Earth in a vertical path (For comparison see figure (a) and (b)).
Answer:

Explanation:
The Hi line of the Balmer series is emitted in the transition from n = 3 to n = 2 i.e.
and 
The wavelength of Hi line of the Balmer series is given by :




So, the wavelength for this line is 550 nm. Hence, this is the required solution.
For a single slit illuminated with a 500 nm light gives a diffraction pattern on a far screen,the angle is mathematically given as
theta=25.3
Option A is correct
<h3> What angle does the 18th minimum occur?</h3>
Generally, the equation for the the angle is mathematically given as

Therefore

In conclusion
theta/7=16/5
theta=10*7/5
theta=25.3
Read more about Angle
brainly.com/question/14362353
Oil is optically denser than water. When sound/light goes from optically denser medium to optically rarer medium, their velocity increase and they moves away for normal.
<h3>
<u>Appropriate</u><u> </u><u>Answer</u><u>:</u></h3>
The sound wave speeds up and bends

As, In optics we learnt that light undergoes refraction when travels from medium of different densities. Similarly, Sound also follows the law of refraction.
- It is due to the change of speed of water in different mediums, This makes it speed up or down depending upon the medium and their densities.
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