Science Chpt 13

Question 1

What is Mechanical Engineering by definition??

Answer 1

A branch of engineering that focuses on the design, production, analysis, working and improvement of a technical object

Question 2

What must mechanical engineering take into account

Answer 2

all aspects of motion, in an object namely the guiding transition, transmission of that motion, changes in speed

Question 3

What is a link?

Answer 3

The mechanical function performed by any component, that connects different parts of an technical object

Question 4

What are the 4 characteristics of links?

Answer 4

1. Direct, indirect
2. Rigid, flexible
3. Removable, non-removable (permanent)
4. Complete, partial

Question 5

What is direct and indirect links?

Answer 5

• Direct: when two parts hold together without a linking component (highlighter)
• indirect: when the parts require a linking component you connect them
  (Scissors)

Question 6

What are rigid and flexible links?

Answer 6

• rigid: when the surfaces of the linkikg component is rigid (scissors)
• flexible: when the surfaces can be deformed (tire)

Question 7

Is are Removable and permanent links?

Answer 7

-Removable: when the parts can separated without further demaging the object (screws, nuts)
- permanent: when separating the link damages the object

Question 8

What is are completely and partial links?

Answer 8

-complete: when the parts cannot move independently when linked
-partial when the parts can move independently when linked

Question 9

What is a degree of freedom and how many are there??

Answer 9

• a degree of freedom is the possible of independent movement (how they can move)
• 6 of them

Question 10

What are the different types of freedom of movement?

Answer 10

• translational: left-right (Tx), top-bottom (Ty), front-back (Tz)
  -rotational: x-axis (Rx), y-axis (Ry), z-axis (Rz)

Question 11

What is a guiding by definition?
What is a guiding component?

Answer 11

-the mechanical function performed by any component that controls the motion of one or more moving parts
-the object that controls the motion of moving parts

Question 12

What are the types of guiding?

Answer 12

• translational guiding: ensure the straight translational motion (sliding door)
  -Rotational guiding: ensures the rotational motion of a moving part (axle on a wheel)
  -helical guiding: ensures the translational motion of guiding while rotating on the same axis (c-clamp)

Question 13

What is adhesion by definition?

Answer 13

• the phenomenon by which two surfaces tend to remain in contact with each other without slipping

Question 14

What is adhesion affected by??

Answer 14

• the nature of the material in contact (if they mesh well together)
• the presence of a lubricant
• temperature (colder temperature less adhesions)
• states of the surfaces in contact
• perpendicular force exerted by one surface to another. (Force applied)

Question 15

What is friction?

Answer 15

• a force that resists the slipping of one moving part over another

Question 16

How do you reduce friction?? And what kinds are there

Answer 16

-adding a lubricant
Kinds: liquid (water, oil), semisolid (Vaseline, animal fat), solid (graphite, paraffin)

Question 17

What is a motion transmission system??

Answer 17

• a system in which the motion stays the same throughout movement

Question 18

What is a driver, driven, and intermediate?

Answer 18

Driver: the component that receives the force required to activate the system
Driven: the component that receives the motion and transfers it on
Intermediate: the one in the middle of them

Question 19

What are the 5 types of motions transmission systems?

Answer 19

-gear train
-chain and sprocket
-worm and worm gear system
-friction gear system
-belt and pulley system

Question 20

Which of the motion transmissions is non-reversible?

Answer 20

-worm and worm gear system

Question 21

What is the definition of reversible in motions systems?

Answer 21

• the driver can become driver

Question 22

What elements are there to consider when building a gear and gear train?

Answer 22

• gear teeth: they must all be identical, same shape, direction, and equally spaced
• gear type: straight gears (rotational axes are parallel), bevel gears (rotation axes are perpendicular)
• gear size: the higher the number of teeth the lower speed of rotation, the larger the diameter of the gear the slower its rotation

Question 23

What do you consider when building a chain and sprocket system?

Answer 23

• the teeth on the system sprocket must be identical
• the chain links must mesh easily with the sprocket teeth
• the system requires frequent lubrication to avoid the rapid wear of the teeth and the chain
• the smaller a sprocket, the faster it turns

Question 24

What are things to consider when building a work and worm gear system?

Answer 24

-the groove of the worm skit fit the gear teeth so that they can mesh
-driver must be the worm

Question 25

What are elements to consider when building a friction gear train?

Answer 25

- gear type: straight, bevel or spherical depending on the axes of the other gears - gear size: the larger the diameter of the gear the slower its rotation -adhesion of the material: friction between the gears must be high

Question 26

What are elements to consider when building a belt and pulley system??

Answer 26

- contain a groove where the belt can fit the groove must be smooth to prevent damage to the belt -the belt must adhere to the pulleys to avoid slipping much as possible - the smaller a pulley the faster it turns

Question 27

What is a speed change?

Answer 27

-occurs in a motions transmission system when the driver does not turn at the same speed as the driven

Question 28

How does the speed change in work and worm gear work?

Answer 28

- for each turn of the worm the worm gear moves the distances of only one tooth. The greater the number of teeth the greater the decrease in speed

Question 29

Does does the speed change happen in friction gear and belt and pulley systems?

Answer 29

-increase: motion is transmitted from one gear or pulley to a gear or pulley of smaller diameter -decrease: motions is transmitted from one gear or pulley to a gear or pulley of larger diameter -no change: motion is transmitted between two gears of the same diameter

Question 30

How does the speed change occur in gear trains and chain sprocket system?

Answer 30

-increase: motion is transmitted from one gear or sprocket to another with fewer teeth -decrease: motion is transmitted from one gear or sprocket to one with more teeth -no change: same amount of teeth

Question 31

How does the speed change occur in gear trains and chain sprocket system?

Answer 31

-increase: motion is transmitted from one gear or sprocket to another with fewer teeth -decrease: motion is transmitted from one gear or sprocket to one with more teeth -no change: same amount of teeth

Question 32

What is torque?

Answer 32

-invokes two forces of equal strength but applied in opposite directions, which causes a component to rotate on an axis

Question 33

What is the difference between engine and resisting torque?

Answer 33

Engine: increases the rotational speed of components Resisting: slows or stop the rotation of components

Question 34

What is a motion transformation system?

Answer 34

When the motion changes in between components of a mechanism

Question 35

Which of the motion transformation systems are reversible?

Answer 35

-rack and pinion -slider crank mechanism

Question 36

What is there to consider when building a rack and pinion system

Answer 36

- the teeth on the rack and on the pinion must be identical -the system requires frequent lubrication to prevent wear -the greater the number of teeth on the pinion the slower its rotation

Question 37

What is there to consider when building a screw gear system?

Answer 37

- the first system type, the nut must be connected to the screw in such a way that the nut cannot rotate -in both systems, the threads of the screw and nuts must match -in the second type, the nut must be fixed in such a way that it’s only Possible motion is rotation

Question 38

Things to consider with a cam and follower system?

Answer 38

- the follower must be guilted in its translational motion -the shape of the cam determines how the follower will move -a device such as a return spring is usually necessary to keep the follower in continual contact with the cam

Question 39

What is the name for special cams?

Answer 39

Eccentrics

Question 40

What is there to consider with a slider crank

Answer 40

-the connecting rod contains two bushings to attach it to the crank and piston -the cylinder must guild the the parts moving in translation -the system requires frequent lubrication