Compound Gears Laboratory - Part 2

Transcription

1 Compound Gears Laboratory - Part 2 Names: Date: About this Laboratory In this laboratory, you will explore compound gear trains, gear ratios, and how the number of teeth on a drive and driven gear affect the output speed of the driven gear. You should first complete the hands-on activity in the pre-laboratory and Part 1 of this laboratory to get a feel for what you will see in the applet. Then you will use technology to assist with further discoveries. Numbers given in the applet are approximations. All explanations are to be made using sentences. ****************************************************************************** Using the Compound Gears Applet - Part 2 Select the radio button in the applet to show 3 Gears. Notice that 4 gears appear in the applet. This is because two gears are joined on a common axle making a compound gear as part of a compound gear train. Point to the horizontal slider bars for Teeth and then set the number of teeth to 36 (the first Drive gear), 24 (the first Driven gear), 12 ( the second Drive gear), and 16 (the second Driven gear). Confirm that you have correctly entered the number of teeth for the Drive and Driven gears. Point to the darkened point on the first gear and drag the wheel counter-clockwise to help you understand why the gears are designated drive and driven in the train. Select Reset to realign the vertical segment indicators. We will designate the first Drive gear as, the first Driven gear as Gear B, the second Drive gear as Gear C and the second Driven gear as. Calculate and then record the following gear ratios in simplest form: # teeth on driven gear # teeth on drive gear Gear B = = Gear C Gears on the same axle, a compound gear, have a gear ratio of 1:1. Why do you think this is the case? Math with Robots Project: Compound Gears Laboratory - Part 2 Pyzdrowski,6/18/2013-1

2 Point to the darkened point on the first gear,, and drag the gear counter clockwise. Count the number of rotations to complete the following statements. Then compare your findings with the ratios. (You may find some surprises.) To align both gears efficiently, rotates times and Gear B rotates times. To align both gears efficiently, Gear B rotates times and Gear C rotates times. To align both gears efficiently, Gear C rotates times and rotates times. In each of the previous cases, what do you notice about numbers in the gear ratio and the number of rotations of the gears? What do you notice about the number of alignment rotations for the two gears, Gear B and Gear C, making up the compound gear? Why do you think this happens? What is the gear ratio of the compound gear set of Gear B and Gear C? Previously you learned that an idler gear acted as both a Driven gear and a Drive gear within a gear train. A compound gear set has each a Driven gear and a Drive gear which are coupled with a gear ratio of 1:1. The compound gear set no longer acts as just an idler gear, but now "chains" the gear ratios through the gear train. To align both gears efficiently, rotates times and rotates times. Notice that if you multiply your "input" gear ratios, you should obtain the final "output" Gear B Gear C gear ratio. That is i i = Gear B Gear C C Is your final Gear output ratio greater than or less than 1? C Does rotate faster or slower than? C Explain your previous answer? Select Reset to realign the vertical segment indicators. Point to the darkened point on the first gear,, and drag the gear counter clockwise one rotation. How many rotations did make? Math with Robots Project: Compound Gears Laboratory - Part 2 Pyzdrowski,6/18/2013-2

3 How many rotations did make? # rotations of The ratio of the in a specific time period is a speed ratio for the gear # rotations of train. What is the speed ratio in this example (as a fraction in simplest form)? What is true about the gear and speed ratios of. Select the radio button in the applet to show 4 Gears. Notice that 6 gears appear in the applet. This is because a compound gear train is formed with two compound gears. We will designate the first Drive gear as, the first Driven gear as Gear B, the second Drive gear as Gear C, the second Driven gear as, the third Drive gear as Gear E, the third Driven gear as Gear F. Set the number of teeth as follows: 36 Gear B 24 Gear C Gear E 16 Gear F 8 To align both gears efficiently, rotates times and Gear B rotates times. To align both gears efficiently, Gear B rotates times and Gear C rotates times. To align both gears efficiently, Gear C rotates times and rotates times. To align both gears efficiently, rotates times and Gear E rotates times. To align both gears efficiently, Gear E rotates times and Gear F rotates times. To align both gears efficiently, rotates times and Gear F rotates times. Notice that if you multiply your "input" gear ratios, you should obtain the final "output" Gear F gear ratio. Show your work. Math with Robots Project: Compound Gears Laboratory - Part 2 Pyzdrowski,6/18/2013-3

4 C Is your Gear F to ratio greater than or less than 1? C Does Gear F rotate faster or slower than? C Select Reset and rotate once. How many rotations does Gear F make? C What is the resultant speed ratio of this compound gear train? C How does the speed ratio compare to the gear ratio of Gear F to? If the initial Drive gear has a speed of 1 rotation per second, show work and determine the speed of the Gear F gear in degrees per second. Math with Robots Project: Compound Gears Laboratory - Part 2 Pyzdrowski,6/18/2013-4

5 Challenge: Select the radio button in the applet to show 4 Gears. Set the number of teeth so that Gear B rotates slower than, rotates faster than Gear C, and Gear F rotates slower than. Number of teeth: Gear B Gear C Gear E Gear F What is the gear ratio? Gear F Math with Robots Project: Compound Gears Laboratory - Part 2 Pyzdrowski,6/18/2013-5