Answer:
(A) L = 115.3kgm²/s
(B) dL/dt = 94.1kgm²/s²
Explanation:
The magnitude of the angular momentum of the rock is given by the foemula
L = mvrSinθ
We have been given θ = 36.9°, m = 2.0kg, v = 12.0m/s and r = 8.0m.
Therefore L = 2.00 × 12 × 8.0 × Sin 36.9° =
115.3 kgm²/s
(B) The magnitude of the rate of angular change in momentum is given by
dL /dt = d(mvrSinθ)/dt = mgrSinθ = 2.00 × 9.8 × 8.0× Sin36.9 = 94.1kgm²/s²
Wavelength = (speed) / (frequency)
Speed of radio = speed of light.
Answer:
in a vacuum
Explanation:
Electromagnetic waves are waves consisting of oscillations of electric and magnetic fields along a plane perpendicular to the direction of propagation of the wave (transverse waves)
Electromagnetic waves are the only waves being able to travel in a vacuum, since they do not need a medium to propagate.
In a vacuum, all electromagnetic waves travel at the same speed, called speed of light, whose value is:

The speed of the waves is actually reduced when they enter a medium, according to

where n is the refractive index of the medium.
Electromagnetic waves are also classified into 7 different types according to their wavelength. From shortest to longest wavelength, we have:
Gamma rays
X-rays
Ultraviolet
Visible light
Infrared
Microwaves
Radio waves