The tearing of paper is physical as it's still paper even when you tear it. A chemical reaction is when the substance is chemically change. ... When paper is burn, the cellulose in the air reacts with the oxygen to form carbon dioxide and water.
It would be physics, if a physical change was occuring to the paper while burning it. It would be biology if it was related to life. But, the main changes are chemical:
While burning paper you change it's composition by creating an interaction between the components of paper and the heat released by the fire. In this reaction we'll see how CO2 affects the composition of paper.
Recall that average velocity is the quantity final position minus initial position, divided by the time it took. So in our case, the cheetah after all the away and back and away again, the mother got a total of: 30 - 10 + 40 = 60 m
and the total time is: 2 + 3 + 1 + 4 = 10 second
Then the average velocity is: 60 m / 10 sec = 6 m/s
Wind is caused by differences in the atmospheric pressure. When a difference in atmospheric pressure exists, air moves from the higher to the lower pressure area, resulting in winds of various speeds. On a rotating planet, air will also be deflected by the Coriolis effect, except exactly on the equator.