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The monkey and hunter a laboratory simulation

Once upon a time a monkey lived in a far off forest. A hunter, having followed the monkey for days finally saw him hanging from a tree. The hunter raised his gun, aimed the barrel at a spot between the monkey's eyes and fired. Now the monkey was an intelligent monkey. He realized that the last moment that he could wait to move to avoid being hit as just after the bullet had left the barrel. This would give him the longest possible time and the hunter cold not affect the path of the bullet by moving the gun.

He let go and fell, just as the bullet left the gun. Unfortunately although he was an intelligent monkey he was no good at physics and the bullet still hit him right between the eyes. Why?

The point is that all objects fall with the same acceleration in this case the monkey and the bullet. As the monkey fell so did the bullet and when the bullet reached the monkey they had both fallen the same distance and so it hit him between the eyes instead of passing over his head!

The diagram shows the laboratory simulation of this with the blowpipe replacing the gun and the tin lid replacing the monkey. The marble breaks the foil link across the mouth of the blowpipe, cutting off the current to the electromagnet and so releasing the tin lid at the same moment.

The slower the bullet the further will the monkey have fallen before the bullet hits him but he will still be hit.

(We have ignored air resistance in this story. Not that it makes much difference to the bullet!!)

schoolphysics: Monkey and hunter animation

To see an animation of the monkey and hunter experiment click on the animation link.

Falling and throwing

An object that is thrown accelerates downwards at the same rate as one that is simply dropped. The horizontal velocity of a projectile stays constant.
An object thrown sideways will take the same time to reach the ground as one that is dropped straight down from the same height and at the same time.
© Keith Gibbs 2011