Lesson 10: Doubling Up

Some compound pulley systems have their final strings pulling down, while others pull upward. Do you think that the direction of the final pull makes any difference in the pulley’s "working" ability? It’s time for you to pull up a seat and find out.

Doing the science

1. Start the Machines Simulation by clicking on the "Sim" tab.
2. Click the "Pulleys" button at the bottom of the screen.
3. Select the bottom-right pulley (Compound, Moveable) from the four pulley buttons at the bottom of the screen.
4. Use the Newton Converter button at the bottom right-hand corner of the screen if you need help converting the hanging mass from kilograms to newtons for the Force on Mass Due to Gravity column.
5. Click the green "Pull" button on the Force Device in the middle of the screen.
6. Note and record in Table 1 the height the 1.0-kg mass lifts off the ground, the applied force and the distance the Force Device pulled the string that is displayed on the Force Device.
7. Click the "Reset" button.
8. Click on the 2.0-kg mass to replace the 1.0-kg mass on the pulley. Repeat the experiment with the 2.0-kg mass.
9. Make sure to note and record your data in Table 1.