Final answer:
The likelihood of a limb breaking increases with distance from the trunk due to greater leverage and torque. Squirrels can jump from heights safely due to their small size, reduced limb stress, and reaching terminal velocity, unlike humans.
Step-by-step explanation:
The likelihood of a thin tree limb breaking when you climb out as far as possible can be explained by physics, specifically by considering leverage and torque. The further out you go on the limb, the longer the lever arm, which is the distance from the pivot point (in this case, the trunk) to the point where the force is applied (where you are situated on the limb). This increased lever arm creates a greater torque, which is the rotational force that can cause the limb to snap. The torque is calculated by multiplying the force (your weight) by the lever arm (distance from the trunk), so a longer lever arm means a greater torque and a higher chance of the limb breaking. Squirrels, however, can jump from tree branches to the ground and run away undamaged due to their small size and the effect of air drag. Compared to humans, squirrels are lighter and present less stress on their limbs upon impact with the ground. Additionally, their small size allows squirrels to reach terminal velocity when falling from heights that would injure a human, like a 5-meter high branch. Terminal velocity is when the upward force of air resistance equals the downward force of gravity, resulting in no further acceleration and lowered impact forces.