April Fool's Day Trick

[Yvon Jean <phys@NTL.SYMPATICO.CA>]

Could you all share your most famous April Fool's Day trick that you have played on your students!

 

Here's one I enjoy to play on my students that have previoulsy been introduced to the stroboscopic effect.

I introduce the trick saying that a new stroboscopic phenomenon has been discovered accidently by an American high school physics teacher and was published in the latest Physics Teacher just received yesterday!  I draw a pendulum on the overhead and tell the students that it will appear to start its motion if they blink their eyes at a certain fixed frequency (equal to the cerebral resonant frequency) and at the same time have their heads move in a large circular motion to about 1/9 th their blinking eyes frequency. When enough students are actually performing, I place over the pendulum a predrawn acetate of a fish hanging from a spring balance hooked to the roof of an  accelerating elevator (I have luckily covered apparent weight in an elevator yesterday!).

I get a blast everytime!  It helps if you prevoiulsy get one or two volunteers among your students to cooperate with the trick. I've even have replies such as ' Sir, it Works!...Try it!...'  I wonder?

Have a good April Fool's Day to you all!

 

Yvon Jean

Kapuskasing , Ontario