In refraction, when a wave travels from one medium to another it changes speed.
Correct option is A.
Answer:
5.0 m/s
Explanation:
The horizontal motion of the salmon is uniform, so the horizontal component of the salmon's velocity is constant and it is

where u is the initial speed and
. The horizontal distance travelled by the salmon is

where d = 1.95 m and t is the time needed to reach the final point.
Re-arranging for t,
(1)
Along the vertical direction, the equation of motion is

where:
y = 0.311 m is the final height reached by the salmon
h = 0 is the initial height
is the vertical component of the initial velocity of the salmon
is the acceleration of gravity
t is the time
Substituting t as found in eq.(1), we get the equation

and we can solve this formula for u, the initial speed of the salmon:

Answer:
The excess charge on earth's surface was calculated to be 4.56 × 10⁵ C
Explanation:
Using the formula for an electric field;
E = kQ/r²
k = 1/(4πε₀) = 8.99 × 10⁹ Nm²/C²
E = 100N/C
r = radius of the earth = 6400 km = 6400000m
Q = Er²/k = 100 × (6400000)²/(8.99 × 10⁹)
Q = 455617.4 C = 4.56 × 10⁵ C
Hope this helps!!!
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