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Science 8 > Mechanical Systems > Flashcards

Mechanical Systems Flashcards

1
Q

what is a lever

A

a simple machine that you use to exert a force on an object in order to move it

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2
Q

what is a fulcrum

A

the fixed point that supports the lever. the lever rotates around the folcrum

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3
Q

What is the effort force

A

the force supplied to any machine to produce movement/action

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4
Q

what is the load

A

the mass of an object that is moved or lifted by a machine

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5
Q

what is the effort arm?

A

it is the distance between the fulcrum and the effort force

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6
Q

what do we call the distance between the fulcrum and the load

A

the load arm

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7
Q

what are the three classes of lever

A

Class 1 = the fulcrum is between the effort and the load (like a seesaw)

Class 2 = the load is between the fulcrum and the effort (wheelbarrow)

Class 3 = the effort force is between the fulcrum and the load (hockey stick or baseball bat)

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8
Q

What type of lever are most of the levers in your body?

A

Class 3

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9
Q

What is canada’s most interesting outerspace lever?

A

The Canadarm (The Space Shuttle Remote Manipulator System). It functions much like a human arm.

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10
Q

What is work?

A

Work = force X distance

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11
Q

How is work measured?

A

work in measured in joules

When you lift one newton a distance of 1 m you have done 1 joule of work

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12
Q

What is an inclined plane?

A

A slope that reduces the force needed to lift something

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13
Q

Suppose that you are a passenger in a SUV gets stuck in the mud. You and the driver use a tree branch to pry the back end out of the mud with both of you pushing on the same end over another tree. (like a class 1 lever) If the truck has a load force of 2500 N and you and the driver apply an effort force of 500N, what would the mechanical advantage be?

A

5

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14
Q

To lift a quad out of the mud, you decide to use a thick branch as a lever. The entire branch is 1.5m long and you rest the branch on a log so that 0.5m is under the edge of the trailer. You are able to push down on the other end of the branch with a force of 300N. What is the maximum force you would apply to the trailer?

A

600N

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15
Q

A grocery store clerk is trying to convince the manager that he deserve a raise because he does more work than the clerk who brings carts into the store. In one hour, the clerk lifts each 10kg bag from a pallet of 50 bags onto a shelf 1.5m off the floor, and the clerk who moves the carts pushes 25 carts each weighing 7kg a distance of 10m from the parking lot into the store. Who does more work, and by how much?

A

The clerk who moves the cart by 10 000 Joules

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16
Q

What is the effect on work when Mechanical Advantage is greater than one

A

work is easier

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17
Q

There are many examples of levers in the human body. Your forearm, bicep and hand form a:

A

Class 3 lever

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18
Q

If a ramp that is 3m long is used to reach a loading dock that is 1.5m high, how much work effort force will be expected to push a crate that has a load force of 1200N onto the loading dock?

A

600N

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19
Q

In a lever, what is the most noticeable difference when you move the fulcrum closer to the load:

A

Work becomes easier

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20
Q

Force is measured using Newtons. How do you convert kilograms to Newtons

A

Option 3

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21
Q

The oars on a row boat are an example of a class 1 lever. Which of the following is another example of a class 1 lever?

A

Scissors

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22
Q

A child pulls a sled up a snow-covered hill. In the process, the child does 405 J of work on the sled. If she walks a distance of 15 m up the hill, how large a force does she exert on the sled?

A

27N

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23
Q

In class 1 and 2 levers, shifting the fulcrum further from the load makes it ________________ to lift the load.

A

Harder

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24
Q 
Which of the following could be the mechanical advantage of a class 3 lever? 
What is the effect on work when Mechanical Advantage is greater than one:
A

work is easier

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25
Q

Two people use a ramp to move a heavy crate onto a truck. If it requires 525N of effort to move the crate, and the ramp is 3m long and reaches a height of 1m. What was the load force is required to move the crate?

A

1575 N

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26
Q

If someone pulled on the rope in this pulley system with a force of 130 N, which of the following is the greatest load could they lift?

A

650N

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27
Q

When using the pulley system, the load was raised 2m off of the ground. How far did they need to pull on the free end of the rope?

A

10m

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28
Q

What is Mechanical Advantage

A

Mechanical advantage (MA) compares the force that is produced by a machine (the load) with the force that is applied to the machine (the effort force)

MA indicates how much a machine can increase or decrease the force on a load, compared with the effort force.

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29
Q

What is the formula for Mechanical Advantage

A

MA=Load force(FL) / Effort Force (FE)

30
Q

What is a Class 1 lever?

A

the fulcrum is between the effort and the load. A pair of scissors is an example of a Class 1 lever

31
Q

How do you convert Newtons

A

Remember to convert Force to Newtons (100g = 1N and 1Kg = 1000g = 10N) and distance to Meters

32
Q

What is a Class 2 lever?

A

always exerts a greater force on the load than the effort force you exert on the lever. In this type of lever, the load is between the effort and the fulcrum, such as a wheelbarrow,

33
Q

What is a class 3 lever?

A

the effort is exerted between the fulcrum and the load, a hockey stick, for example

34
Q

What is input work?

A

The work you do on the machine

35
Q

What is output work

A

The work the machine does on the load

36
Q

Do you use units in Mechanical Advantage calculations?

A

no, they are a ratio

37
Q

What are ergonomics?

A

The science of designing machines to suit people

38
Q

What is a winch

A

A winch consists of a small cylinder and a crank or handle.

39
Q

What is a gear?

A

A gear is a rotating wheel-like object with teeth around its rim.

40
Q

What is a gear train?

A

A group of two or more gears is called a gear train.

41
Q

What is the first gear in a gear train called?

A

The driving gear (often called the driver)

42
Q

What is the second gear called in a gear train

A

The second gear is called the driven gear (often called the follower).

43
Q

What is a sprocket ?

A

A gear with teeth that fit into the links of a chain is called a sprocket.

44
Q

What is speed ratio?

A

Speed ratio = Number of driver gear teeth / Number of follower gear teeth

45
Q

What is a pulley?

A

a pulley is a grooved wheel with a rope or a chain running along the groove.

46
Q

What is a fixed pulley?

A

A fixed pulley is attached to something that does not move, such as a ceiling, a wall, or a tree.

47
Q

What is a movable pulley

A

A movable pulley is attached to something else, often by a rope that goes around the pulley itself.

48
Q

What is kinetic energy

A

Kinetic energy is a form of energy that an object or a particle has by reason of its motion.

If work, which transfers energy, is done on an object by applying a net force, the object speeds up and thereby gains kinetic energy.

49
Q

What is potential energy

A

potential energy, stored energy that depends upon the relative position of various parts of a system.

A spring has more potential energy when it is compressed or stretched. A steel ball has more potential energy raised above the ground than it has after falling to Earth.

50
Q

What is energy transmission

A

In energy transmission, the energy is transferred from one place to another, and no energy is changed or converted.

51
Q

What is efficiency

A

The efficiency of a machine tells you how much of the energy you gave to the machine was transferred to the load by the machine.

52
Q

Is any machine 100% efficient?

A

no

53
Q

How do you calculate efficiency

A

Efficiency = Work done by lever on load / Work done on lever by effort force × 100%

54
Q

What are low efficiency machines

A

Low-efficiency machines lose much of the work put into them because of friction; high-efficiency machines do not.

55
Q

What is a way to boost efficiency in machines

A

add some sort of lubricant

56
Q

Why do machines lose efficiency

A

because of friction or other loss of transfer energy

57
Q

Can friction be useful

A

Yes

Many sports and outdoor activities use friction in a useful way. Baseball players and gymnasts rub a powder called rosin on their hands to increase friction and improve their grip.

58
Q

What is pressure?

A

The force(F) acting over a certain area(A)

59
Q

What is the equation for force?

A

The equation for pressure is written as: Pressure=Force/Area or p=F/A

60
Q

What is force measured in?

A

Newtons

61
Q

What is a pascal (Pa)?

A

The unit for pressure (Newtons/m squared)

62
Q

What is a kilopascal?

A

1000Pa

63
Q

What is Pascal’s Law?

A

Pascal’s law states that pressure exerted on a contained fluid is transmitted undiminished in all directions throughout the fluid and perpendicular to the walls of the container.

64
Q

What is a hydraulic lift?

A

A hydraulic lift is a mechanical system that raises heavy objects, such as a vehicle on a service station lift.

65
Q

What is a closed system?

A

A closed system is a self-contained collection of parts.

66
Q

What is an example of a closed system?

A

Your body

67
Q

What is a hydraulic system?

A

A hydraulic system is a drive technology where a fluid is used to move the energy from e.g. an electric motor to an actuator, such as a hydraulic cylinder.

68
Q

what is a pneumatic system

A

A pneumatic system is a collection of interconnected components using compressed air or gas to do work for automated equipment.

69
Q

Give four examples of pneumatic devices.

A

Nail gun, Dentist Drill, Jack hammer and Hovercraft

70
Q

List four instruments or machines that use hydraulics.

A

Tractor, Bulldozer, Airplane wing flaps and Garbage Truck

71
Q

What is a subsystem

A

When a simple machine is part of a large system, we call it a subsystem.

72
Q

How does a steam engine work

A

In a steam engine, fuel such as coal or wood is burned to heat water in a boiler outside the engine. The water changes to steam and drives the engine

Science 8 (3 decks)

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