The centripetal acceleration is 
Explanation:
For an object in uniform circular motion, the centripetal acceleration is given by

where
v is the speed of the object
r is the radius of the circle
The speed of the object is equal to the ratio between the length of the circumference (
) and the period of revolution (T), so it can be rewritten as

Therefore we can rewrite the acceleration as

For the particle in this problem,
r = 2.06 cm = 0.0206 m
While it makes 4 revolutions each second, so the period is

Substituting into the equation, we find the acceleration:

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M1*V1 + M2*V2 = M1*V + M2*V.
1400*25 + 1800*20[180+40]=1400*V+1800*V.
Divide both sides by 100:
14*25 + 18*20[220o] = 14V + 18V.
350 + 360[220o] = 32V.
350 - 276-231i = 32V.
74 - 231i = 32V.
242.6[-72.2o] = 32V.
V = 7.6m/s[-72.2o]=7.6m/s[72o] S. of E.
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.