Question

A monkey in a perch 20 m high in a tree drops a coconut above the head of a zoo keeper as he runs with a speed 1.5 m/s beneath the tree actually intending to hit the toes of the zoo keeper, how early in seconds should the coconut be dropped by the monkey

Answer 1

Answer on Question#41060 – Physics – Mechanics | Kinematics | Dynamics

A monkey in a perch 20 m high in a tree drops a coconut above the head of a zoo keeper as he runs with a speed 1.5 m/s beneath the tree actually intending to hit the toes of the zoo keeper, how early in seconds should the coconut be dropped by the monkey

Solution:

Time the coconut should be dropped by the monkey before zoo keeper will run beneath the tree = time for the coconut to hit the ground:

Equation of motion for the coconut along the Y-axis:

$$y: h = \frac {g t ^ {2}}{2}$$ $$t = \sqrt {\frac {2 h}{g}} = \sqrt {\frac {2 \cdot 2 0 m}{9 . 8 \frac {m}{s ^ {2}}}} = 2. 0 2 s$$

Therefore, it takes 2.02 seconds for the coconut to hit the ground (and two seconds for the zookeeper to run, because these actions are happening simultaneously), hence, the monkey should drop the coconut 2.02 seconds before zoo keeper will run beneath the tree.

Answer: 2.02s