Answer:
The answer is A
Explanation: hope this helps :)
By definition, the wavelength of an electromagnetic wave is calculated using the following formula:
Where:
\lambda = wavelength
c = speed of light = 
f = frequency of the wave.
This relation means that the division of the wavelength λ between the frequency f is always equal to the speed of light.
Thus:
the velocity v of this wave must be equal to c.
Finally the correct answer is D. 
Chemical energy called exothermics
Answer:
Explanation: what is the question?
Answer:
a) T = 2 π√ (m / k) c) T = 2 s
, f = 0.5 Hz
Explanation:
a) In an oscillatory system the angular velocity is
w = √ (k / m)
where w is the angular velocity, k the constant of the spring and m the applied mass
the angular velocity is related to the frequency and the period
w = 2π f
f = 1 / T
w = 2π / T
we substitute
2π / T = √ k / m
T = 2 π√ (m / k)
b) The units If kilograms (m = [kg]) are for the masses, the spring constant is in Newton per meters (k = [N / m], angular velocity in (w = [rad / s]
c) they ask us the period if we have 10 cycles in 5 s
T = 10/5
T = 2 s
f = 1 / T
f = 0.5 Hz
