What advantage do you get from using a lever? - Try this!

 Try this!


The Weight-Changing Orange

Materials

  • small orange

  • ruler or flat wooden stick

  • thick book

Instructions

An orange is easy enough to lift, but can we make it feel heavier?  Try this:


1. Hold out a flat wooden stick (such as a ruler). Balance the orange on the stick right near your hand. Wiggle the stick up and down slightly. How heavy does the orange feel?


2. Move the orange to the middle of the stick and repeat the wiggle. Now, how heavy does the orange feel?


3. Move the orange to the very end of the stick and repeat the wiggle. Now, how heavy does the orange feel?

The orange felt heavier and heavier, didn't it?  That's because you were using a class 3 lever.  (The effort force is in the middle.)


Class 3 levers are not good for lifting heavy things, but they do move things faster.  Did you notice that when you wiggled the stick up and down just a small amount, the orange moved a large amount at the far end of the stick?

Now for a challenge!  Can you repeat this activity to make the orange feel lighter?  Here's a hint:  Set up a class 2 lever (load in the middle) by putting the far end of the stick on a thick book.


Now, try lifting the end of the stick with the orange in various places and give close attention to how heavy the orange feels and how much it moves.