Answer:
80%
Explanation:
Efficiency = Power output / Power input × 100 %
To calculate efficiency we need to find power output of electric pump.
We can use,
Work done = Energy change
Work done per second = Energy change per second
Work done per second = Power
Therefore, Power = Energy change per second
= Change in potential energy of water per second
=mgh / t
= 200× 10×6 / 10
= 1200 W = 1.2 kW
Now use the first equation to find efficiency,
Efficiency = × 100%
= 80 %
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:
#LearnwithBrainly
Answer:
F = 0.00156[N]
Explanation:
We can solve this problem by using Newton's proposed universal gravitation law.
Where:
F = gravitational force between the moon and Ellen; units [Newtos] or [N]
G = universal gravitational constant = 6.67 * 10^-11 [N^2*m^2/(kg^2)]
m1= Ellen's mass [kg]
m2= Moon's mass [kg]
r = distance from the moon to the earth [meters] or [m].
Data:
G = 6.67 * 10^-11 [N^2*m^2/(kg^2)]
m1 = 47 [kg]
m2 = 7.35 * 10^22 [kg]
r = 3.84 * 10^8 [m]
This force is very small compare with the force exerted by the earth to Ellen's body. That is the reason that her body does not float away.