The Monkey and Zookeeper

An Introduction

A GIF Animation

There is an interesting monkey down at the zoo. The monkey spends most of its day hanging from a limb of a tree. The zookeeper feeds the monkey by shooting bananas from a banana cannon to the monkey in the tree. This particular monkey has a habit of dropping from the tree the moment that the banana leaves the muzzle of the cannon. The zookeeper is faced with the dilemma of where to aim the banana cannon in order to hit the monkey. If the monkey lets go of the tree the moment that the banana is fired, then where should she aim the banana cannon?

To ponder this dilemma, consider the following questions.

Throw at the Monkey in a Gravity Free Environment

If there were no gravity, then what would happen if the banana was shot at the monkey? What path would the banana take and would it hit the monkey?

Throw above the Monkey with Gravity On

If there was gravity acting upon both the monkey and the banana (the usual situation), then what would happen if the banana was shot above the monkey? What paths would the banana and the monkey take? Would the banana fall (below the straight-line path) and hit the monkey as the monkey drops from the tree? Or would the banana miss the monkey, passing over his head?

Throw at the Monkey at a Fast Speed with Gravity On

If there was gravity acting upon both the monkey and the banana (the usual situation), then what would happen if the banana was thrown at the monkey with a fast speed? What paths would the banana and the monkey take? Would the banana fall (below the straight-line path) and hit the monkey as the monkey drops from the tree? Or would the banana merely move in a straight line and hit the monkey immediately? Or would the banana miss the monkey, passing over his head (or even below his head)?

Throw at the Monkey at a Slow Speed with Gravity On

If there was gravity acting upon both the monkey and the banana (the usual situation), then what would happen if the banana was thrown at the monkey with a slow speed? What paths would the banana and the monkey take? Would the banana fall (below the straight-line path) and hit the monkey as the monkey drops from the tree? Or would the banana not have enough speed to hit the monkey as it was falling (presumably, because the monkey would fall faster than the slow banana)?

Click on any of the above links to explore the zookeeper's dilemma.

For more information on physical descriptions of motion, visit The Physics Classroom. Detailed information is available there on the following topics:

Projectiles

Characteristics of a Projectile's Trajectory

Other animations can be seen at the Multimedia Physics Studios