Mr. Mak's Grade 8 Science Website

Gears Explain what gears are. (p. 20) What materials are gears typically made of? (p. 20) What are gears typically used for? (p. 20) List at least four example of real-life machines that use gears. Explain what a gear train is. Quickly sketch a simple two-gear train. (p.20/figure 5) Explain what a gear ratio is. (p. 20) A bicycle is an example of a two-gear train connected by a chain. If your front (driver) gear has 10 teeth, and the follower (back) gear has 50 teeth, how many times must your pedal the front gear around to have the back gear rotate once? Explain how you know. (figure 5) If your front (driver) gear has 60 teeth, and the follower (back) gear has 15 teeth, how many times will the rear gear rotate when the front gear turns once? Explain how you know. (figure 6) Fill in the blanks. With a __________ gear ratio, the gear can be turned with less ________ but must go a longer __________. (figure 6a) Fill in the blanks. With a __________

Wheel and Axles 1.      List three types of simple machines that are used for transmitting rotational motion. (p. 18) 2.      What is the MA for all these groups of machines? 3.      In these groups of machines the __________________ must move over a greater _______________ than the _________________. (p. 18) 4.      Briefly explain what the two main parts of a wheel and axle system are. Include a quick sketch. (p. 18 / figure 1) 5.      Answer the question below figure 2. (p. 18) 6.      List four or more examples of common wheel-and-axle systems. (p. 18) 7.      Explain how one of the three systems from the previous question work. (p. 18) 8.      Wheel and axle system can change: rotary movement into ___________ movement OR rotary movement into _____________________ OR linear motion into _______________ (p. 18) 9.      Solve for the velocity ratio in figure 3. (p. 18 / p. 12 – formula) Pulley Systems 1.      Give two examples of where pu

  Know the formula for mechanical advantage (MA) Know how to solve MA problems Know the units for MA Understand and explain the difference between the size of the load force and effort force when the MA is greater than 1, exactly 1 and less than 1 Identify and understand the difference between class 1, class 2 and class 3 levers Know two examples of class 1, class 2 and class 3 levers Explain the purpose of using levers Label the fulcrum, effort force, load force, effort arm and load arm on a lever diagram Helpful videos: https://www.youtube.com/watch?v=YlYEi0PgG1g https://www.youtube.com/watch?v=J2Nt_rRa3JY

Hydraulic Machine Build Report Name and Class: 1.    1. What did you make? 2.    2.   Function (what does it do)? 3.     3. Explain what makes your project a hydraulic machine. 4.    4. Explain what role hydraulics play in your machine. 6.    5.   Expand on the one aspect of your project you found most challenging and briefly explain why. 6. Explain how you overcame the challenge in question #6. 7.     7. If you were to rebuild your structure, describe two things you would do differently to end up with a better final product. 8.    8.   Briefly describe any new hands-on skills you learned or improved upon through this project (i.e. –measuring, sawing, drilling, glue gun, using a mitre box, scroll saw, band saw, drill press, etc.).