Answer:
The length of the shadow is decreasing 8 metres per second.
Step-by-step explanation:
In the attached figure, we draw the situation of the bear approaching the tree.
We can use the Tales to make some calculations.
The proportion between the height of the bear (h) and his shadow (S) is equal to the proportion between the height of the flashlight (H) and the sum of the distance of the bear (d) and the bear shadow.
This can be written as:
If we clear S we have:
We know that the distance is a function of time and it is reduced, as the bear approaches the tree, as a rate of 6 m/s.
We can express then the rate of variation of the shadow S as:
The length of the shadow is decreasing 8 metres per second.
