Answer: B
Explanation: i learned it last year
Let us start from considering monochromatic light as an incidence on the film of a thickness t whose material has an index of refraction n determined by their respective properties.
From this point of view part of the light will be reflated and the other will be transmitted to the thin film. That additional distance traveled by the ray that was reflected from the bottom will be twice the thickness of the thin film at the point where the light strikes. Therefore, this relation of phase differences and additional distance can be expressed mathematically as

We are given the second smallest nonzero thickness at which destructive interference occurs.
This corresponds to, m = 2, therefore


The index of refraction of soap is given, then

Combining the results of all steps we get

Rearranging, we find



Complete Question:
A 10 kg block is pulled across a horizontal surface by a rope that is oriented at 60° relative to the horizontal surface.
The tension in the rope is constant and equal to 40 N as the block is pulled. What is the instantaneous power (in W) supplied by the tension in the rope if the block when the block is 5 m away from its starting point? The coefficient of kinetic friction between the block and the floor is 0.2 and you may assume that the block starting at rest.
Answer:
Power = 54.07 W
Explanation:
Mass of the block = 10 kg
Angle made with the horizontal, θ = 60°
Distance covered, d = 5 m
Tension in the rope, T = 40 N
Coefficient of kinetic friction, 
Let the Normal reaction = N
The weight of the block acting downwards = mg
The vertical resolution of the 40 N force, 





Power, 

The Earth is a sphere is a statement to describe a scientific law
Answer:
The force applied to the surface is 9 kilo Newton.
Explanation:
While jumping on the surface the player applies the force that is equal to its weight on the surface.
The mass of the player is given as 90 kg.
Force applied by the player = weight of the player
Force applied by the player = m × g
Where m is the mass of the player and g is acceleration due to gravity
Force applied by the player = 90 × 9.8
Force applied by the player = 882 Newton
Expressing your answer to one significant figure, we get
Force applied by the player =0. 9 kilo Newton
The force applied to the surface is 0.9 kilo Newton.