This is an example of resonance - when one object vibrating at the same natural frequency of a second object forces that second object into vibrational motion. The result of resonance is always a large vibration.
Answer D. Forced vibrations, such as those between a tuning fork and a large cabinet surface, result in a much lower sound than was produced by the original vibrating body Because this statement contridicts the above statement, it is not accurate
The answer is C. the earths mantle because the wood in this case is the surface
Answer:
F = 1,875 N
Explanation:
force=

∆H = m∆V
where ∆H ----> change in momentum.
( final momentum - initial momentum )
and ∆V ----> change in velocity
( final velocity - initial velocity )
and m ----> is mass
then f =

= 1,875 N
Answer:
C. It speeds up, and the angle increases
Explanation:
We can answer by using the Snell's law:

where
are the refractive index of the first and second medium
is the angle of incidence (measured between the incident ray and the normal to the surface)
is the angle of refraction (measured between the refracted ray and the normal to the surface)
In this problem, light moves into a medium that has lower index of refraction, so

We can rewrite Snell's law as

and since

this means that

which implies

so, the angle increases.
Also, the speed of light in a medium is given by

where c is the speed of light and v the refractive index: we see that the speed is inversely proportional to n, therefore the lower the index of refraction, the higher the speed. So, in this problem, the light will speed up, since it moves into a medium with lower index of refraction.