Answer: A
Explanation: We know that f=p*n
f=50*300=15000 Hz = 15kHz.
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A sphere has reflection symmetry across any plane through its center.
Into molecules of
sugar and
oxygen.
The complete reaction of the photosynthesis is in fact:

and the energy of the light coming from the sun is also used to make the reaction possible.
Answer:
K = 36 J
Explanation:
In this exercise we must use the conservation of mechanical energy at two points at initial x = 0 and the end point of maximum compression of the spring
Initial x = 0
Em₀ = K = ½ m v²
Final point of maximum compression
= Ke = ½ k x²
Em₀ = 
K = ½ k x²
We put the kinetic energy because it is a data, let's look for the spring constant
k = 2 K / x²
k = 2 9 / d²
k = 18 / d²
Let's calculate the kinetic energy, so that the compression is x = 2d
K = ½ k x²
K = ½ (18 / d²) (2d)²
K = ½ 18/d² 4d²
K = 36 J