Answer:
They have a sour taste as in the case of citric acid in orange and lemon.
They change the color of litmus paper from blue to pink, methyl orange to red, and make phenolphthalein colorless.
They are corrosive.
They cause burns to the skin.
Larger index of refraction means slower light-speed in that material.
According to this chart, it's fastest in air and slowest in <em>diamond</em>.
I see the light moving exactly at speed equal to c.
In fact, the second postulate of special relativity states that:
"The speed of light in free space has the same value c<span> in all inertial frames of reference."
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The problem says that I am moving at speed 2/3 c, so my motion is a uniform motion (constant speed). This means I am in an inertial frame of reference, so the speed of light in this frame must be equal to c.
Work is equal to the force applied to an object multiplied by the distance it had travelled. This is work as long as the force and the direction of the distance in going in the same direction.
It is work because you're applying a force on an object to move it.
For example, work is done when you push a box across the floor, but work is not done when you lift the box up and then walk it across the room. This is because the force on the box is upwards since you're lifting it and the direction of the distance is left or right so the directions are not the same.
