Answer:
they are used in periscopes,for signalling,in kaleidoscopes,to see round dangerous bends
Explanation:
It was a man named <span>Johannes Kepler. </span>
Answer:
Air at higher altitude is under less pressure than air at lower altitude because there is less weight of air above it, so it expands (and cools), while air at lower altitude is under more pressure so it contracts (and heats up).
Explanation:
Hope that helped
