Thursday, July 30, 2009
Simple Machines: Pulleys!
On to the last column of our simple machines: Pulleys! My son said, "I love pulleys, I don't know why." Maybe it is because pulleys are fun! When you see a flag raised up the flagpole it is being pulled up with pulleys.
A pulley is a wheel with a groove in its edge. A rope fits into the groove. When the rope is pulled, the wheel turns. Anything attached to the end of the rope (the load) is moved. There are two kinds of pulleys: a fixed pulley & a block and tackle.
A fixed pulley is attached (like the flag pole) & can only be moved in one direction...as in up & down. In the block & tackle there are two or more pulleys...one is fixed & the other is attached to the load (or the item being moved). These pulleys are the block & the ropes that connect them is called the tackle. The more ropes & pulleys used the easier the job will be.
Sometimes it is hard to recognize pulleys around you. Here are some other examples that maybe you have not thought of. Curtain rods, tow trucks, mini-blinds, & cranes. Draw or cut out photos to paste to your chart. Look around & list as many as you can on your chart.
As you see on your chart there is one last column left empty. We will be working on that later but as for now we are done with our columns of the six simple machines. I hope you had fun...check back to finish the last column.