Question(s) of the Day • Answer the following questions on a piece of paper and put your name at the top. You have 8 minutes to complete the questions of the day. Good luck! Read page 455 and answer the following questions: 1) Why is the mechanical energy from an electric motor considered “greener” than energy from a combustion engine? Give two reasons. 2) How can you counteract the harmful effects of combustion engines when you choose a means of transportation? Give three examples. Answer 1) Why is the mechanical energy from an electric motor considered “greener” than energy from a combustion engine? Give two reasons. Answer: The mechanical energy from an electric motor does not emit greenhouse gases and does not require the extraction and transportation of fossil fuels. Answer 2) How can you counteract the harmful effects of combustion engines when you choose a means of transportation? Give three examples. Answer: By opting for public transit or carpooling when possible – by respecting the speed limit on the road – by making sure that car tires are properly inflated. Ch. 13 – Mechanical Engineering • • • • • • • Question of Day Recuperation after school Notes on Chapter 13 – Links & Gears Web Exploration # I-3 (FL) – Speed Assignment Chapter 13 -#1 Quiz next class on Assignment ch.13 - 1 What do you want to learn – sign up Characteristics of Links Direct versus Indirect Links. What’s the difference? A direct link only features the two parts being joined. An indirect link has a third part that helps link them together. Classify as Direct or Indirect? Link between tire and wheel Direct link between blade & shoe Indirect (due to screw) More Examples: Classify as direct or indirect. c) The link between the two gears indirect d) The link between the two gears direct Rigid versus Flexible Links. What’s the difference? • The rigid link cannot be bent. The flexible link is bendable like rubber. Examples: Classify as rigid or flexible. Link between tire and wheel link between blade and shoe Flexible Rigid More Examples: Classify as rigid or flexible. c) The link between the two gears d) The link between the two papers Flexible overall Flexible Removable versus Nonremovable Links. What’s the difference from the point of view of destruction? The nonremovable link cannot be removed without wrecking what’s linked. Examples: Classify as removable or nonremovable. Link between tire and wheel link between blade and shoe Removable Removable Examples: Classify as removable or nonremovable. Link between shoe top and sole Non removable link between nut and bolt Removable Complete Versus Partial Links. What’s the difference? • A partial link allows one component to move without necessarily moving the other. A complete link has both parts moving together. Classify as complete or partial links and explain why. Complete Complete Classify as complete or partial links and explain why. Partial Partial Look at the bottle of correction fluid opposite. b) Name the characteristics of the link between the cap and the bottle. Bottle 1) Direct 2) Rigid 3) Removable Cap Brush stem 4) Partial Look at the bottle of correction fluid opposite. a) Name the characteristics of the link between the cap and the brush stem. Bottle 1) Direct 2) Rigid 3) Non-Removable Cap 4) Complete Brush stem Don’t forget: We have a quiz on assignment 13 # 1 next class. You must hand in the completed Assignment before the Quiz starts. Class Work Complete Assignment Chapter 13 - #1 2) Football is a sport that requires a lot of equipment, including a helmet. Inside the helmet is a layer of flexible padding to protect the player’s head. It is held in place with glue. What are the characteristics of the link between the padding and the helmet? Explain each characteristic. • a) Direct or indirect? Indirect, because a linking component is needed to attach the padding to the helmet. • b) Rigid or flexible? Flexible, because the surface of the padding can be deformed. • c) Removable or non-removable? Non-removable, because if someone tries to remove the padding, the linking component and possibly also the padding would break. • d) Complete or partial? Complete, because the padding cannot move independently of the helmet. 4) During a family breakfast, you explain that there are three main types of guiding. You use the jar of peanut butter with its screw-on lid, the cutlery drawer, the refrigerator door and the kitchen scissors as examples. Which type of guiding does each of these objects demonstrate? • a) jar of peanut butter Answer: Helical guiding • b) cutlery drawer Answer: Translational guiding • c) refrigerator door Answer: Rotational guiding • d) kitchen scissors Answer: Rotational guiding 6) One characteristic an engineer may look for in the design of a technical object is a significant change in rotational speed between the parts. The two systems below have been proposed to meet this purpose. • System 1 System 2 a) Which type of motion transmission systems are they? Answer: Gear trains • b) In which system is the change in rotational speed between the gears greater? Explain your answer. Answer: The speed decreases more in system 2 because there is a greater difference in the number of teeth on the two gears. A company has lost its computer data on the rotational speed of the B components in the systems below. Using the information provided in the drawings of these systems, calculate the rotational speed of the B components. B A 15 turns/minute Answer: 7.5 turns per minute