When a ray passes from air into glass the direction in which the light ray is travelling changes. The light ray appears to bend as it as it passes through the surface of the glass. ... This 'bending of a ray of light' when it passes from one substance into another substance is called refraction.
watts = work per second.
work is mgh = 3x10x50=1500
watts out = 1500
Watts used = 2000
eff=1500/2000=75%
This causes the fluid to increase its speed. Bernoulli's principle tells us that an increase in the speed of a fluid happens at the same time with a reduction in pressure or a reduction in the fluid's potential energy. This necessitates that the amount of kinetic energy, potential energy and internal energy stays persistent.
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