MECHANICAL SYSTEMS PART B TEST

Question 1

what is energy?

Answer 1

energy is the ability to do work. it provides the force to do work.

Question 2

what is work?

Answer 2

the amount of force needed to move an object a certain distance. without energy there is no work.

Question 3

what is potential energy?

Answer 3

stored energy. much of the energy for machines as well as our bodies is stored as chemical energy.

Question 4

what is kinetic energy?

Answer 4

energy of movement

Question 5

four forms of kinetic energy.

Answer 5

thermal, mechanical, electrical, magnetic

Question 6

four forms of potential energy

Answer 6

chemical, elastic, nuclear, gravitational

Question 7

what has to happen to energy to make a machine work?

Answer 7

energy must be transferred to a machine to make it work. however, we need to store energy to make the machine work only when we want it to.

Question 8

is energy created/destroyed or transformed/transferred

Answer 8

transformed/transferred

Question 9

will the amount of energy you start with be different or the same amount you end with?

Answer 9

the amount of energy you start with is the amount of energy you end with

Question 10

will the type of energy change or will the amount?

Answer 10

the type of energy might change, but the amount will not.

Question 11

what does it mean to be efficient?

Answer 11

efficiency is a measurement of how well a machine works without wasting energy. (fancy way of saying it: refers to the proportion or percentage of input energy that is transmitted to the intended output.

Question 12

why do we want our machines to be efficient?

Answer 12

the more efficient a machine is, the more energy is transferred to the load.

Question 13

can machines be 100% efficient?

Answer 13

no, no machine is perfectly efficient, some energy is always lost (changed into other form) Ex. heat.

Question 14

when we use simple machines, is the energy transferred from us to the machine to the load or is there a loss?

Answer 14

there is always a loss. One of the main reasons is friction.

Question 15

what will the answer for efficiency always be?

Answer 15

A PERCENT!! %%%%

Question 16

what reduces the efficiency of a machine?

Answer 16

FRICTION!

Question 17

how can we boost efficiency?

Answer 17

reduce friction by using lubricants, decrease the number of moving parts, keep machines clean.

Question 18

how is friction useful?

Answer 18

we often need friction to make a machine work properly.

Question 19

what are some examples of how friction can be useful?

Answer 19

vehicle tires to make them grip and move, gymnasts put powder on their hands to improve grip and increase friction, running shoes so you have grip and don’t slip.

Question 20

what is pressure?

Answer 20

force acting over a certain area.

Question 21

what is another way to show pressure (besides pascals)

Answer 21

Newtons/m2

Question 22

when does pressure increase?

Answer 22

pressure increases when there is more force over less area

Question 23

what are devices designed to do? (relating to pressure)

Answer 23

devices are designed to spread the force over a larger area. (ex. football helmets, hockey shoulder pads, air bags.)

Question 24

why does the person not get hurt when they lay on a bed of nails compared to when they step on one nail and get hurt?

Answer 24

because, the pressure is spread over a larger area rather than being reduced to one spot.

Question 25

what is a hydraulic system?

Answer 25

uses liquids in a confined space under pressure to transfer a force (uses liquid to do work)

Question 26

why do hydraulic systems use a liquid?

Answer 26

they use a liquid because its incompressible and can transmit pressure. ex. cherry picker, car lifts, circulatory systems

Question 27

what is a pneumatic system?

Answer 27

pneumatic systems use gas under high pressure to transfer a force. (uses air to do work)

Question 28

how do pneumatic systems use air?

Answer 28

air passes through the pneumatic device under high pressure and then escapes out the device. ex. jack hammer, air nailers, air compressors, sand blasters, respiratory system.

Question 29

how do hydraulics work in a braking system?

Answer 29

when you press the brake, the oil presses on pistons which apply pressure to the wheels which slows you down.

Question 30

how do pneumatics work with a jackhammer?

Answer 30

the compressor is powered by a motor which draws in air. that air is compressed and channeled through a tube which powers the jackhammer bit.

Question 31

what is pascals law?

Answer 31

when a fluid is compressed, the pressure pushes out in all directions throughout the fluid. (ex. think of a water balloon when you squeeze it)

Question 32

what systems use this law?

Answer 32

mechanical systems use pascals law.

Question 33

what is a complex machine?

Answer 33

a complex machine is a machine made of two or more simple machines working together. (like the rube Goldberg machines)

Question 34

what is a system?

Answer 34

a complete device with an overall function (ex. CAN OPENER [system - the can opener relies on kinetic energy of someone squeezing the device closed around the rim of a can and then cranking the handle to perform its function of opening a can])

Question 35

what is a subsystem?

Answer 35

parts of a system that perform 1 specific task - a system can have many subsystems (ex. CAN OPENER [ cutting mechanism; gears grip the can while the blade cuts into it])

Question 36

what is a component?

Answer 36

components are the individual parts that make up a system or subsystems (ex. CAN OPENER [screw, gears, handle {wheel and axle}])

Question 37

do fluids become compressed?

Answer 37

no, fluids do not become compressed, unlike gasses

Question 38

what happens with the pushing fore within the fluid?

Answer 38

the pushing force (pressure) is transmitted equally in all directions within the fluid [SUPER IMPORTANT]

Question 39

do systems that move large objects use a hydraulic or pneumatic system?

Answer 39

most machines that move large objects use a hydraulic system

Question 40

hydraulic system definition?

Answer 40

system that uses a liquid under pressure to move loads.

Question 41

what was used before hydraulic systems?

Answer 41

before hydraulic systems, most construction was done by hand (ex. pyramids, castles, great wall of china)

Question 42

pneumatic system definition?

Answer 42

system that uses gas under pressure to move loads

Question 43

similarities between hydraulic and pneumatic systems?

Answer 43

both use fluid to transfer power, both can control movement + force, both have many industrial manufacturing applications.

Question 44

pneumatic system differences?

Answer 44

use air, smaller, lower maintenance, louder, lower pressure

Question 45

hydraulic system differences?

Answer 45

use liquid (often oil), larger, higher maintenance, better for heavy-duty applications, higher pressure.

Question 46

complex machines?

Answer 46

a type of mechanical system where simple machines all work together. it consists of multiple interconnected components and subsystems. These systems are designed to perform a specific function, using mechanical advantage to make the task easier.

Question 47

system

Answer 47

when a group of parts work together to perform a function (ex. bike brakes.)

Question 48

subsystem

Answer 48

parts of a system that perform 1 specific task (ex. gear in bike). subsystems usually transfer energy or a force (linkages, transmissions.)

Question 49

transmission

Answer 49

transfer of force and energy from the engine in a vehicle to the wheels.

Question 50

ergonomics

Answer 50

this science of designing machines to suit people is called ergonomics. designers have become very concerned with making sure machines or products fit the person using them. (ex. it is important to prevent work-related conditions like carpal tunnel syndrome or other preventable situations [eg. braces])