Answer:
Explanation:
Total internal reflections is a phenomenon where incident light rays when travelling from a denser medium or from a medium with higher refractive index to less dense medium or a medium with lesser refractive index ( The indices of refraction have the relation n₁ > n₂, where n₁ is the refractive index of the first medium and n₂ is the refractive index of medium 2) leads to the light ray being reflected back into the first medium instead of undergoing refraction. Usually, this occurs when the incident light rays angle to the normal is greater than a certain critical angle which is the angle when the refracted ray angle in the second medium is 90°
Answer:
True
Explanation:
Since the definition of work in physics is the magnitude of force applied to an object and multiplied by the distance than the object is moved, if the object remains in the same place although there is a force acting on it, there will be not work done.
Answer:
324 people
Explanation:
radius r = diameter / 2 = 45cm /2 = 22.5 cm or 0.225 m
We can calculate the total volume of the log by computing the volume of each cylindrical log:

So the total volume of all 12 logs is

The weight that the raft can support, is the buoyancy force subtracted by its own weight.
The buoyancy force is basically the weight of the water is displaced, which is water density times volume. The log weight is also log density times its volume

where
are the density of water and raft, respectively. But since we have the specific gravity of wood is 0.6. That measn


Therefore 
Let g = 9.8m/s2. We can now calculate the force that the raft can support

Each person has a mass of 68kg, their weight would be
W = 68*g = 68*9.8 = 666.4N
So the maximum number of people that the raft can hold is
F / W = 216129.2 / 666.4 = 324 people
It's a chemical chemical change
Answer:
13.6 cm
Explanation:
From Snell's law:
n₁ sin θ₁ = n₂ sin θ₂
In the air, n₁ = 1, and light from the horizon forms a 90° angle with the vertical, so sin θ₁ = sin 90° = 1.
Given n₂ = 4/3:
1 = 4/3 sin θ
sin θ = 3/4
If x is the radius of the circle, then sin θ is:
sin θ = x / √(x² + 12²)
sin θ = x / √(x² + 144)
Substituting:
3/4 = x / √(x² + 144)
9/16 = x² / (x² + 144)
9/16 x² + 81 = x²
81 = 7/16 x²
x ≈ 13.6