In snowy and cold temperatures eg mount everest
The correct option is D.
The critical angle is defined as the angle of incidence, which provides an angle of refraction of 90 degree. At any angle of incidence greater than the critical angle, all the light will totally reflected, resulting in total internal reflection.Thus, the critical angle is equal to the refractive index.
Answer:
![\theta = 106.3 degree](https://tex.z-dn.net/?f=%5Ctheta%20%3D%20106.3%20degree)
Explanation:
As we know that
![\vec w = -\hat i + 7\hat j](https://tex.z-dn.net/?f=%5Cvec%20w%20%3D%20-%5Chat%20i%20%2B%207%5Chat%20j)
![\vec v = 7\hat i - \hat j](https://tex.z-dn.net/?f=%5Cvec%20v%20%3D%207%5Chat%20i%20-%20%5Chat%20j)
also we know that
![\vec v. \vec w = -14](https://tex.z-dn.net/?f=%5Cvec%20v.%20%5Cvec%20w%20%3D%20-14)
it is given as
![\vec v. \vec w = (-\hat i + 7\hat j).(7\hat i - \hat j)](https://tex.z-dn.net/?f=%5Cvec%20v.%20%5Cvec%20w%20%3D%20%28-%5Chat%20i%20%2B%207%5Chat%20j%29.%287%5Chat%20i%20-%20%5Chat%20j%29)
![\vec v. \vec w = - 7 - 7 = -14](https://tex.z-dn.net/?f=%5Cvec%20v.%20%5Cvec%20w%20%3D%20-%207%20-%207%20%3D%20-14)
also we can find the magnitude of two vectors as
![|v| = \sqrt{(-1)^2 + (7)^2}](https://tex.z-dn.net/?f=%7Cv%7C%20%3D%20%5Csqrt%7B%28-1%29%5E2%20%2B%20%287%29%5E2%7D)
![|v| = \sqrt{50}](https://tex.z-dn.net/?f=%7Cv%7C%20%3D%20%5Csqrt%7B50%7D)
similarly we have
![|w| = \sqrt{(7^2) + (-1)^2}](https://tex.z-dn.net/?f=%7Cw%7C%20%3D%20%5Csqrt%7B%287%5E2%29%20%2B%20%28-1%29%5E2%7D)
![|w| = \sqrt{50}](https://tex.z-dn.net/?f=%7Cw%7C%20%3D%20%5Csqrt%7B50%7D)
now we know the formula of dot product as
![\vec v. \vec w = |v||w| cos\theta](https://tex.z-dn.net/?f=%5Cvec%20v.%20%5Cvec%20w%20%3D%20%7Cv%7C%7Cw%7C%20cos%5Ctheta)
![-14 = (\sqrt{50})^2cos\theta](https://tex.z-dn.net/?f=-14%20%3D%20%28%5Csqrt%7B50%7D%29%5E2cos%5Ctheta)
![\theta = cos^{-1}(\frac{-14}{50})](https://tex.z-dn.net/?f=%5Ctheta%20%3D%20cos%5E%7B-1%7D%28%5Cfrac%7B-14%7D%7B50%7D%29)
![\theta = 106.3 degree](https://tex.z-dn.net/?f=%5Ctheta%20%3D%20106.3%20degree)
It can be purified or be used by a filter
Answer:
18.43m
Explanation:
At the initial stage, the car accelerates at 2.0 m/s² for 6.7 seconds, to get the velocity of the car at this point, we will use the equation of motion;
v = u + at
v = 0+(2.0)(6.7)
v = 13.4m/s
The velocity of the car during this time is 13.4m/s.
Also, if the car slows down at a rate of 1.5m/s², we can also calculate the time it took for the car to decelerate (check the attachment for diagram).
v = u+at
v = 0
u = 13.4m/s
a = -1.5m/s² (deceleration is negative acceleration)
0 = 13.4+-1,5t
-13.4 = -1.5t
t = 13.4/1.5
t = 8.93s
Hence it took the car 8.93s to slow down for the next stop sign.
To calculate how far apart the stop signs are, we need to calculate the total distance AD according to the diagram
Distance covered = AD = 18.43m
HENCE THE STOP SIGNS ARE 18.43m apart