Answer:
A) d = 11.8m
B) d = 4.293 m
Explanation:
A) We are told that the angle of incidence;θ_i = 70°.
Now, if refraction doesn't occur, the angle of the light continues to be 70° in the water relative to the normal. Thus;
tan 70° = d/4.3m
Where d is the distance from point B at which the laser beam would strike the lakebottom.
So,d = 4.3*tan70
d = 11.8m
B) Since the light is moving from air (n1=1.00) to water (n2=1.33), we can use Snell's law to find the angle of refraction(θ_r)
So,
n1*sinθ_i = n2*sinθ_r
Thus; sinθ_r = (n1*sinθ_i)/n2
sinθ_r = (1 * sin70)/1.33
sinθ_r = 0.7065
θ_r = sin^(-1)0.7065
θ_r = 44.95°
Thus; xonsidering refraction, distance from point B at which the laser beam strikes the lake-bottom is calculated from;
d = 4.3 tan44.95
d = 4.293 m
We can find the average speed of the body by finding the total distance covered, and then dividing it by the total time of the motion.
The total distance covered is:

while the total time of the motion is

So, the average speed of the body is:
Answer:
Angular acceleration is defined as the rate of change of angular velocity of a body.
consider the attached figure as shown
It rotates with an angular velocity
An point inside the object rotates along the path as indicated thus turning by an angle
in time 't'
Thus we have

physically angular acceleration can be understood as the rate at which the angular speed of any object is changing with time.
Since work involves force moved through a distance, none of them technically does ANY work.