Transcript Mech. Engineering(April.24)

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
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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