Answer:
(A) 7.9 m/s^{2}
(B) 19 m/s
(C) 91 m
Explanation:
initial velocity (U) = 0 mph = 0 m/s
final velocity (V) = 85 mph = 85 x 0.447 = 38 m/s
initial time (ti) = 0 s
final time (t) = 4.8 s
(A) acceleration =
= = 7.9 m/s^{2}
(B) average velocity =
= = 19 m/s
(C) distance travelled (S) = ut +
= (0 x 4.8) + = 91 m
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.