The sky can turn a multitude of colors such as red, orange, purple and yellow (especially near sunset or sunrise) when the light must pass through a much longer path (or optical depth) through the atmosphere. You must have seen The black Sky, The Blue Sky, The Red Sunset, The White Horizon. Have you ever wondered why? Click picture to explore!
Coil a string of beads into a jar, then jerk one end out of the jar and towards the floor. What happens is what you would expect—the chain starts sliding out of the jar.
But then something unexpected follows—instead of continuing to slide over the rim of the jar, the beads leap up into the air like a fountain before curving back towards the floor.
This is a pretty simple concept, but it looks really mind boggling in action. The chain is under the action of three different forces.
1. Gravity which is pulling the leading edge of the chain towards the floor.
2. As each chain link is acted upon by gravity, a second force pulls it along the bead behind it.
3. The third force is inside the jar – the jar is actually propelling the beads into air. How? That's tricky!
Imagine the sun at its best wearing down a traveler who is trying to cross an infinite desert. He gasps for breath and water. Wow! he finds a lake at a distance. In disbelief, he blinks his eyes but still can see it there.
It was not hallucination but mirages are actually optical illusions which result due to refraction of light through different layers of air at different temperature.
Cold air is denser than warm air, and therefore has a greater refractive index. This means that as light travels from cool to hot air, it gets bent upwards towards the denser air and away from the ground (see diagram).
Forces always occur in pair. In a game of tug of war, each team exerts force on the other. If no team is moving towards other team, it means they both are exerting equal forces and hence no movement takes place. This is a case of balanced forces but when one of the team is dragged to the other side, the team which got dragged applied less force which is the case of unbalanced forces.
To sum up, balanced forces result in no net movement.
A cell is the basic structural and functional unit of life. Animal cells and plant cells both are eukaryotic cells and have similar organelles. Generally, animal cells are smaller than plant cells.
Contrary to animal cells which come in various sizes and tend to have irregular shapes, plant cells are more similar in size and are typically rectangular or cube shaped. A plant cell also contains structures not found in an animal cell. Let us see in the picture.
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