Answer:

Explanation:
As we know that the speed of the rocket is v1 and v2 at the bottom and top of the window
then we will have



also we know that


now we have

also we have

now if the sill of the window is at height 8 m from the ground then we have



Answer: 0.48W
useful power output=total power output*efficency
useful power output=2.4W*0.20=0.48W
Answer:
Position at t= 4 seconds is 144 m
Explanation:
It is given that acceleration, a = 18 t, where t is the time.
We know that Velocity, 
Substituting value of a,
Velocity, 
We know that at t = 0, v = -12 m/s
So, 
So velocity, 
We also know that displacement, 
Substituting value of v,
Displacement, 
We know that at t = 0, particle is at origin, x =0.
So, 
Displacement, 
At t = 4 seconds

Position at t= 4 seconds is 144 m
Refraction refers to C. the bending of light rays when they pass from one medium into another
Explanation:
Refraction is a phenomenon typical of wave. Refraction occurs when a wave travels through the boundary between two different mediums. When this occurs, the wave changes speed, wavelength and direction (but the frequency remains the same).
In particular, the direction of the refracted ray is determined by Snell's Law:

where
is the index of refraction of the 1st medium
is the index of refraction of the 2nd medium
is the angle of incidence, which is the angle between the direction of the incident wave and the normal to the boundary
is the angle of refraction, which is the angle between the direction of the refracted wave and the normal to the boundary
Therefore, the correct description of refraction is
C. the bending of light rays when they pass from one medium into another
Learn more about refraction:
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