Answer:
19.95 J
Explanation:
The center of mass of the ladder is initially at a height of:

The center of mass of the ladder ends at a height of:
=L/2
So, the work done is equal to the change in potential energy which is:
W = PE = 
now 
therefore
W = [mgL/2]×[1 - sin(theta)]
W = [(7.30)(9.81)(2.50)/2]×[1-sin(51°)]
solving this we get
W = 19.95 J
Answer: 18.27°
Explanation:
Given
Index of refraction of blue light, n(b) = 1.64
Wavelength of blue light, λ(b) = 440 nm
Index of refraction of red light, n(r) = 1.595
Wavelength of red light, λ(r) = 670 nm
Angle of incident, θ = 30°
Angle of refraction of red light is
θ(r) = sin^-1 [(n(a)* sin θ) / n(r)], where n(a) = index of refraction of air = 1
So that,
θ(r) = sin^-1 [(1 * sin 30) / 1.595]
θ(r) = sin^-1 (0.5 / 1.595)
θ(r) = sin^-1 0.3135
θ(r) = 18.27°
The acceleration due to gravity would be 5.95 m/s²
A force is known to be a push or pull and it is the change in momentum per time. It can be expressed by using the relation.
- Force = mass × acceleration.
From the parameters given:
- Mass = 105 kg
- Force = 625 N
By replacing the given values into the above equation, we can determine the acceleration.
∴
625 N = 105 kg × acceleration.

acceleration = 5.95 N/kg
acceleration = 5.95 m/s²
Learn more about acceleration(a) here:
brainly.com/question/14344386
Velocity = Frequency x Wavelength
= 18 x 13 = 234 mm/s
I see the light moving exactly at speed equal to c.
In fact, the second postulate of special relativity states that:
"The speed of light in free space has the same value c<span> in all inertial frames of reference."
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The problem says that I am moving at speed 2/3 c, so my motion is a uniform motion (constant speed). This means I am in an inertial frame of reference, so the speed of light in this frame must be equal to c.