LEGO, the LEGO logo are trademarks of the LEGO Group. 2011 Merry-Go-Round
Merry-Go-Round Merry-Go-Round Introduction The material is designed for students in Grades 2 through 8. Working in pairs, children of any academic background from eight years and up can build, investigate and learn from the models. Simple & Powered Machines enables children to work as young scientists, engineers, and designers. It provides them with settings, tools and tasks that promote design technology, science and mathematics. They make assumptions and predictions. They design and make models and then observe the behavior of these models; they reflect and re-design, and then record and present their findings. Description In this activity you will build the Merry-Go-Round. You will investigate the mechanisms used in this model and focus on the gears. Objectives Getting familiar with basic gears and crown gears Investigate and reflect to get knowledge about gear ratio, gearing up and gearing down. Vocabulary The following words will be used in the activity and might need explaining: Drive gear Driven gear Crown gear Gear ratio Gear up Gear down Centrifugal force LEGO, the LEGO logo are trademarks of the LEGO Group. 2011
Merry-Go-Round Curriculum links Technology Physical Science Inquiry Communication Students: write/program a logical set of steps. work with a technology design. explore the way things work. experience science through technology. Students should be taught to: describe the motion of objects move objects by pushing, pulling, throwing, spinning, dropping, and rolling; and describes the motion. describe the change in position of objects when moved. explain gearing up and gearing down. explain the motion of driver and follower gears, spur and crown gears. explain gear ratios and how that relates to gearing up and gearing down. explain the effect of centrifugal force on objects. Students: use critical thinking, scientific reasoning, and problem solving to make informed decisions. explore a topic through teamwork. brainstorm. build and test a model. develop the skills necessary to do full inquiry. ask a simple question, complete an investigation, answer a question, and share the results with others. Students: communicate verbally ideas and discuss the benefits and weaknesses of proposed solutions. interpret illustrations. LEGO Materials Required 9686 LEGO Education Simple & Powered Machines LEGO, the LEGO logo are trademarks of the LEGO Group. 2011
Merry-Go-Round Connect Jack and Jill are on their way home from school. When walking through the park they pass the travelling fun fair that is visiting town. Jack and Jill can see that people are setting up the different amusements. In particular one of the amusements is getting their attention: the Merry-Go-Round. Both Jack and Jill love Merry-Go-Rounds. Unfortunately the park is not open yet, so Jack and Jill decide that they will make their own Merry-Go-Round when they get home. In the UK and Europe, merrygo-rounds usually turn clockwise, while in North America the typically go counter-clockwise - looked on from above. Now try the following: Build a Merry-Go-Round that spins, when you turn the handle. Describe which mechanisms are used to rotate the Merry-Go-Round Examine how many times the rides rotate when the handle is rotated once. Here are some other ways of connecting: When was the last time you tried a Merry-Go-Round? Where do we usually find them? What is the fun thing about a ride in a Merry-Go-Round? How do you feel after a ride? Talk about differences between the Merry-Go-Rounds we find at a playground and the ones that we find at a fun fair. How do they work? LEGO, the LEGO logo are trademarks of the LEGO Group. 2011
Merry-Go-Round Construct Build the model Build the Merry-Go-Round following the building instructions step 1-13. Check that all elements are firmly linked to one another and make sure that the teeth of the gears fit together. When the Merry-Go-Round has been built, notice how gear systems are used. Gear stystems are simple machines. Our model Uses a handle to turn an axle... The axle turns a gear The gear drives another gear... The other gear is placed on an axle This axle drives a crown gear The crown gear drives another crown gear This crown gear is attached to an axle The axle is spinning the Merry-Go-Round LEGO, the LEGO logo are trademarks of the LEGO Group. 2011
Merry-Go-Round Contemplate Investigate how the gears work. How many teeth does the drive gear have? How many teeth does the driven gear have? How many teeth does the drive crown gear have? How many teeth does the driven crown gear have? How many times do the rides rotate, when you rotate the handle once? What is a crown gear, and what do we use them for? Continue Look at the building instruction (step 14) Can you by changing the gears make the merry-go-round spin more or fewer rounds on one rotation on the handle? The drive gear is the gear that is turned by an outside effort, for instance your hand or an engine. Any gear that is turned by another gear is called a driven gear or follower. The drive gear provides the input force and the driven gear delivers the output force. If you want to make an angle gearing, you ll need crown gears or bevel gears. They transfer the speed and force unchanged, but at an angle of 90 o If the drive gear(g1) has 24 teeth and the driven gear(g2) has 8 teeth, 1 one rotation with the handle will cause g1/g2 = 24/8 = 3 rotations Record your findings in a grid: Ex. Number of teeth on drive gear Number of teeth on driven gear Number of rotations with handle Number of carousel rotations Keeping the 24/8 gearing and changing the crown gear as well to g1=20 and g2=12 we will get: 24/8 x 20/12 = 5 rotations 1 How many times do the rides rotate, when you rotate the handle once? And if you change the crown gears too what happens? How many times do the rides rotate, when you rotate the handle once now? Explain why. Optional: Allow the groups to adjust the model and to use gears of their own choice from the 9686-box. LEGO, the LEGO logo are trademarks of the LEGO Group. 2011
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