mechanical engineering - mottsworld · web viewnonslip stair treads are installed in a staircase to...

© E

RPI R

epro

duct

ion

and

adap

tatio

n pe

rmitt

ed

sole

ly fo

r cla

ssro

om u

se w

ith Observatory

.

ANSWER KEY

Name: ________________________________________ Group: _______________ Date: ____________

Mechanical engineering

Checkup

1 WHAT IS MECHANICAL ENGINEERING? (p. 426)

1. Name the branch of science and technology that focuses specifically on the study of technical objects with moving parts. Mechanical engineering

2 LINKING IN TECHNICAL OBJECTS (pp. 427–430)

2. Look at the bicycle opposite.a) Name the four characteristics of the link

between the tires and their respective wheels. Explain each characteristic.

b) Name the four characteristics of the link between the brake housing and lever. Explain each characteristic.

CHAPTER 13Checkups and follow-ups Mechanical engineering

1Observatory / Guide11129-B

Direct, because there is no linking component

between the two parts.

Flexible, because the surface of the tire can be

deformed.

Removable, because it is possible to separate the

two parts without damaging them.

Complete, because it prevents the independent

motion of one of the two parts.

Indirect, because there is a linking component between the two parts (the bolt).

Rigid, because the surfaces of the two parts cannot be deformed.

Removable, because it is possible to separate the two parts without damaging them.

Partial, because the brake lever can move independently.

ANSWER KEY

Checkups and follow-ups ESTQuestions 1–13, 15–17 and A–E

CHAPTER 13

Brakehousing

Bolt

Brake lever

Headtube

Tire

Wheel

Welding

Crossbar

© E

RPI R

epro

duct

ion

and

adap

tatio

n pe

rmitt

ed

sole

ly fo

r cla

ssro

om u

se w

ith Observatory

.

ANSWER KEY

Name: ________________________________________ Group: _______________ Date: ____________

c) Name the characteristics of the link between the crossbar and the head tube. Explain each characteristic.

3. How many degrees of freedom does the front wheel of the bicycle in question 2 have? Explain your answer.

3 GUIDING CONTROLS (pp. 431–435)

4. Look at the three objects below.

a) For each of the three objects, name the type of guiding involved.

b) Identify the guiding component in each object.

CHAPTER 13Mechanical engineering Checkups and follow-ups

2 Observatory / Guide11129-B

Faucet: a nut

Pliers: a rivet

Combination square: a ruler

Indirect, because there is a linking component between the two parts (the welding).

Rigid, because the surfaces of the two parts cannot be deformed.

Non-removable, because it is impossible to separate the two parts without damaging them.

Complete, because it prevents the independent motion of one of the two parts.

The front wheel has only one degree of freedom of movement because it can rotate only frontward and

backward. There is therefore only one possibility of independent motion of the wheel in relation to the

part it is connected to.

1 2 3

Faucet: helical guiding

Pliers: rotational guiding

Combination square: translational guiding

Square head

Ruler

Rivet

Lever 2

Lever 1

HandleNut

© E

RPI R

epro

duct

ion

and

adap

tatio

n pe

rmitt

ed

sole

ly fo

r cla

ssro

om u

se w

ith Observatory

.

ANSWER KEY

Name: ________________________________________ Group: _______________ Date: ____________

5. In each of the following statements, what factor causes the strength of the adhesion between two surfaces to vary?a) Nonslip stair treads are installed in a staircase to prevent accidents.

b) Cross-country skis usually glide better in colder weather.

c) To avoid injury, it is best not to wear leather-soled shoes when playing sports in a gym.

d) Each spring, Yuri oils his bicycle chain to protect it from premature wear.

6. In gymnastics competitions—for example, in the high bar event—athletes cover their hands with powder.a) What is the mechanical function of the powder?

b) How is the powder useful during this event?

4 MOTION TRANSMISSION SYSTEMS (pp. 435–445)

7. The motion transmission system opposite is used to direct the chute of a snow blower.a) What is this type of motion transmission system called?

b) Name the driver component in this system. What colour is it in the illustration? (See the colour illustration in the student book, p. 451.)



The state of the surfaces in contact

The temperature

The nature of the materials in contact

The presence of a lubricant

Lubrication

It reduces the friction between the athletes’ hands and the bar, helping the gymnasts perform better.

A worm and worm gear system

The driver component is the worm (screw), which is red in the illustration.

© E

RPI R

epro

duct

ion

and

adap

tatio

n pe

rmitt

ed

sole

ly fo

r cla

ssro

om u

se w

ith Observatory

.

ANSWER KEY

Name: ________________________________________ Group: _______________ Date: ____________

c) Name the driven component in this system. What colour is it in the illustration? (See the colour illustration in the student book, p. 451.)

The driven component is the worm gear, which is blue in the illustration.

d) Does the system contain an intermediate component? If so, what is it called?This system does not contain an intermediate component.

e) If the snow blower user decides to turn the chute manually, the motion transmission system could be damaged. Explain your answer.

8. Antonia is asked to build a gear train using two of the gears illustrated below.

a) Which gears should she choose for her system?

b) Which characteristic of the gears would motivate her choice?

9. Among the motion transmission systems below, identify those whose rotational motions are correctly illustrated.



The shape of the teeth

If force is applied to the chute to direct it, the worm gear will be forced to act as the driver of the

motion transmission system. However, the driver of a worm and worm gear system is always the

worm, and this type of system is irreversible. Trying to force it to reverse could therefore break it.

A B C

Gears A and C

a) b) c) d)

Systems b) and d)

© E

RPI R

epro

duct

ion

and

adap

tatio

n pe

rmitt

ed

sole

ly fo

r cla

ssro

om u

se w

ith Observatory

.

ANSWER KEY

Name: ________________________________________ Group: _______________ Date: ____________

10. Look at the mechanism opposite.a) Which type of motion transmission system is used in this

technical object?

b) Which type of gear is used in this system?

11. Based on the information provided, calculate the ratio of the gear speeds for each of the motion transmission systems below.

In a), the ratio of the gear speeds from the larger gear to the smaller gear is 2:1. In b), the ratio from

the larger pulley to the smaller pulley is 5:1.

12. Look at the two worm and worm gear systems opposite. In which system will the rotational speed be more greatly reduced? Explain your answer.

13. In the chain and sprocket system opposite, the rotational speed of the driver sprocket is 60 revolutions per minute. Based on the information provided by the illustration, calculate the rotational speed of the other sprocket. Express your answer in revolutions per minute.

Question 14 is not intended for students in the EST program.



A gear train

a) b)

The reduction in speed will be greater in system a) because

the worm gear in this system has more teeth than the gear in

system b).

The rotational speed of the driven sprocket is

45 revolutions per minute.

a) b)

Bevel gears

Driver sprocket

© E

RPI R

epro

duct

ion

and

adap

tatio

n pe

rmitt

ed

sole

ly fo

r cla

ssro

om u

se w

ith Observatory

.

ANSWER KEY

Name: ________________________________________ Group: _______________ Date: ____________

5 MOTION TRANSFORMATION SYSTEMS (pp. 445–449)

15. Look at the motion transformation system opposite.a) What is this type of motion transformation system

called?

b) Which of the two gears will turn faster? Explain your answer.

16. A tensioner is used to tighten the wire or rope of a clothesline, as in the illustration opposite. Which type of motion transformation system is at work here?A screw gear system

17. Look at the motion transformation systems below.

a) What are these motion transformation systems called?

b) Which of the four systems involves an eccentric? Explain your answer.

c) What does the spring do in these systems?

d) In which of the four systems will the rod rise the highest?



A rack and pinion system

Gear A will turn faster because it has fewer teeth.

A B C D

Cam and follower systems

System B involves an eccentric because the rotational axis of the cam is off-centre.

It ensures the constant pressure of the follower on the surface of the cam or the eccentric.

In system B

© E

RPI R

epro

duct

ion

and

adap

tatio

n pe

rmitt

ed

sole

ly fo

r cla

ssro

om u

se w

ith Observatory

.

ANSWER KEY

Name: ________________________________________ Group: _______________ Date: ____________

REVIEW QUESTIONS A. Look at the bottle of correction fluid opposite.

a) Name the characteristics of the link between the cap and the brush stem.

b) Name the characteristics of the link between the cap and the bottle.

c) Which part acts as a guiding control in this object?

d) Which type of guiding is involved?

e) What characteristic of the guiding component controls the guiding?

B. Referring to the correction fluid bottle in question A, how many degrees of freedom do the following parts have? a) the cap when screwed on the bottle

b) the brush stem when attached to the cap

C. Glue sticks are among the most popular types of glue. In the tube, the glue stick is attached to a nut. Twisting the screw at the base of the tube will make the glue stick move up or down.a) What is the usual mechanical function of glue in

technical objects?

b) Which part guides the glue stick motion, and which type of guiding is involved?

c) Is the system for raising or lowering the glue stick a motion transmission system or a motion transformation system? Identify the type of system at work.

d) Name the four characteristics of the link between the cap and the tube.



Direct, rigid, non-removable and complete

Direct, rigid, removable and partial

The bottle (more specifically, the mouth of the bottle).

Helical guiding

Its threads

Two—one rotation and one translation along the same axis

None

Linking

The tube acts as the guiding component. It guides the glue stick

in a translational motion.

It is a motion transformation system—specifically, a screw gear system.

Direct, rigid, removable and partial

Brush stemCap

Bottle

© E

RPI R

epro

duct

ion

and

adap

tatio

n pe

rmitt

ed

sole

ly fo

r cla

ssro

om u

se w

ith Observatory

.

ANSWER KEY

Name: ________________________________________ Group: _______________ Date: ____________

D. Referring to the glue stick in question C, answer the following questions.a) How many degrees of freedom does the nut in the tube have? Describe them.

b) How many degrees of freedom does the cap have when it is placed on the tube? Describe them.

c) Explain why it is important for there to be adhesion between glue and parts to be glued.

E. Prepare your own summary of Chapter 13 by building a concept map.

Follow-up 1. Why is the mechanical energy from an electric motor considered “greener” than energy from a

combustion engine? Give at least two reasons.

2. How can you counteract the harmful effects of combustion engines when you choose a means of transportation? Give several examples.



Answers will vary. Example: The mechanical energy from an electric motor does not emit greenhouse

gases and does not require the extraction and transportation of fossil fuels.

Answers will vary. Examples: by opting for public transit or car-pooling when possible

– by respecting the speed limit on the road

– by making sure that car tires are properly inflated.

See the Concept maps section in Guide B.

Only one: a translation along a single axis

Two: one translation and one rotation along the same axis

If there were no adhesion between the glue and the parts to be glued, the glue would simply slide

over the parts and fail to act as a linking component.

mechanical engineering - mottsworld · web viewnonslip stair treads are installed in a staircase to...

Documents