See how a block and tackle system can increase your mechanical advantage. You will need two broomsticks, a rope, and two helpers. A. Give each helper a broom stick and have them stand facing each other holding the broomstick firmly in both hands in a horizontal position. The broomsticks should be at the same level, about two feet apart.

B. Tie one end of the rope to one of the broomsticks. (You may need to have one of your helpers hold the knot firmly in one hand as he or she holds the broomstick to help anchor it.)

C. Wrap the rope around the other broomstick, as in a simple pulley system, and pull on the free end of the rope. Your helpers should resist your pulling. What happens? Can you pull the broomsticks together?

D. Now weave the rope back over the first broomstick, so you have a double pulley. Pull on the free end. What happens now? Can you pull the broomsticks together? What is your mechanical advantage?

E. Try weaving the rope over the broomsticks one or two more times. Describe what happens, and state the mechanical advantage of each situation.

F. Write a summary of what happened and an explanation using the terms:

force
distance
work
mechanical advantage