Why can't bird see glass

Birds see whatever is reflected on the glass surface. Not what’s behind it.

Explanation:

Birds can't see glass. Instead, they see whatever happens to be reflected in its mirror-like surface. Often, this is open sky or trees, which, if you're a bird, are appealing (and perfectly safe) things to fly towards.

explanation:

as the height from which the ruler was dropped increased, the speed of the ruler at ryan's hand increased.

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg