What is the frequency of an electromagnetic wave that has a wavelength of 300,000 km? (the speed of light is 300,000 km/s.)?
1 answer:
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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
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
