Answer:
8 seconds, Answer choice C.
Explanation:
The information they give us about the speed of the cat, is from the point at which the dog started chasing it (that velocity being 10 m/s).
Notice that the actual distance the cat run is: 100 meters minus 20 meters (100 - 20 = 80 meters). Therefore, we have information on the distance covered by the cat (80 meters), and its speed (10 m/s), so we can use the definition of speed to find the time it took the cat to get to the tree:
[tex]speed=\frac{distance}{time} \\10 \frac{m}{s} = \frac{80\,m}{time}\\time=\frac{80}{10} s=8 \,s[/tex]
Since all units for the physical quantities involved were given in the SI system, the answer comes also in the SI units of time: "seconds"
