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Science > Simple Machines SG > Flashcards

Simple Machines SG Flashcards

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1
Q

How do you know if work has been done?

A

The object moves as force is applied and the object moves in the direction of the force.

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2
Q

What does work depend on?

A

Force and distance

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3
Q

How can you get more power?

A

Exert a greater amount of work/force through a given time or decrease the time it takes to do a certain amount of work.

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4
Q

What is the equation for work?

A

F x d

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5
Q

What is the unit used to express work?

A

Joule

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6
Q

What is power?

A

The rate at which work/energy is transformed.

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7
Q

How can power be calculated?

A

W/t

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8
Q

What unit is used to express power?

A

Watt

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9
Q

What is a machine?

A

A device that makes work easier by changing the six or direction of a force.

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10
Q

What is work input?

A

The work you do on a machine.

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11
Q

What is input force?

A

The force you apply to a machine through a distance.

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12
Q

What is work output?

A

Th work done by the machine on an object.

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13
Q

What is output force?

A

The force applied by a machine through a distance.

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14
Q

Why is work output for a machine always less than work input?

A

Some of the work done by the machine is used to overcome frictions.

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15
Q

How do machines make work easier?

A

They change the size or direction of the input force.

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16
Q

Using a machine doesn’t mean what?

A

You do less work

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17
Q

What can a machine increase?

A

Force and distance but not at the same time.

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18
Q

When force is increased then what happens to distance?

A

It decreases

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19
Q

What is mechanical advantage?

A

How many times the machine multiplies the force input

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20
Q

What is the function of mechanical advantage?

A

Output force divided input force

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21
Q

The larger the mechanical advantage…..

A

The more it can help move or lift a heavy object.

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22
Q

As mechanical, advantage increases, the distance the output force move the object ……

A

Increases

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23
Q

What is the mechanical advantage if the output force is equal to the input force?

A

1

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24
Q

If the input force is greater than the output force, the mechanical advantage is what?

A

Less than 1

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25
Q

What is the relationship between the work output and input?

A

The work output is always less than the work input.

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26
Q

What is some of the work done by the machine used to overcome?

A

The friction created by the use of the machine.

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27
Q

What equals work input?

A

The work output plus the work done to overcome friction.

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28
Q

What is mechanical efficiency?

A

The comparison of a machine’s work output with the work input.

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29
Q

What is the equation of mechanical efficiency?

A

(Work output divided by work input) x 100

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30
Q

What does mechanical efficiency tell?

A

What percentage of the work input gets converted into work output

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31
Q

How can you increase mechanical efficiency?

A

By reducing the amount if friction

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32
Q

What are the 6 simple machines?

A

Levers, inclined plane, wedge, screw, wheel and axle, and pulley

33
Q

What is a lever?

A

A simple machine that has a bar that pivots at a fixed point called a fulcrum

34
Q

What are levers used for?

A

To apply a force to a load

35
Q

What is a first class lever?

A

The fulcrum is between the input force and the load

36
Q

What does a first class lever change?

A

Always changes the direction of the input force and depending on the location of the fulcrum, first class levers can be used to increase force or increase distance.

37
Q

Examples of first class levers.

A

Balance and boat oars

38
Q

What is the mechanical advantage of a first class lever?

A
  • when the fulcrum is closer to the load than to the input force, the MA is greater than 1
  • when the fulcrum is exactly in the middle, the MA is 1
  • when the fulcrum is closer to the input force than the load, the MA is less than 1
39
Q

Why is the mechanical advantage of a first class lever greater than 1 when the fulcrum is closer to the load?

A

The output force is increased because it is exerted over a shorter distance.

40
Q

Why is the MA of a first class lever 1 when the fulcrum is exactly in the middle?

A

The output force is not decreased because the input force’s distance is not increased.

41
Q

Why is the MA of a first class lever less than 1 when the fulcrum is closer to the input force?,

A

Although the output force, is less than the input force, distance increases.

42
Q

What is a second class lever?

A

The load is between the fulcrum and the input force.

43
Q

Examples of second class lever.

A

Wheelbarrow and bottle cap opener

44
Q

What do second class levers change?

A

They DON’T change the direction of the input force. They allow you to apply less force than the force exerted by the load. Because the output force is greater than the input force, you must exert the input force over a greater distance.

45
Q

What is the mechanical advantage of a second class lever?

A

It is greater than 1

46
Q

Why is the mechanical advantage of a second class lever greater than 1?

A

The closer the load is to the fulcrum, the more force is increased and the greater the MA.

47
Q

What is a third class lever?

A

The input force is between the fulcrum and the load.

48
Q

Examples of third class levers.

A

Hammer hitting a nail, an arm

49
Q

What does a third class lever change?

A

It DOESN’T change the direction of the input force or increase the input force. Therefore the output force us always less than the input force.

50
Q

What is the mechanical advantage of a third class lever?

A

Less than 1

51
Q

Why is the mechanical advantage of a third class lever less than 1?

A

Force is decreased

52
Q

What is an inclined plane?

A

A simple machine that is a straight, slanted surface which facilitates the raising of loads; a ramp

53
Q

How do inclined planes make work easier?

A

By requiring a small input force to use over a long distance

54
Q

What is the mechanical advantage of incline planes?

A

Divide the length of the inclined plane by the height to which the load is lifted. (the greater the ratio, the greater the mechanical advantage)

55
Q

What is a wedge?

A

A simple machine that’s made up of 2 inclined places and that moves; often used for cutting.

56
Q

What does a wedge apply?

A

An output force greater than the input force

57
Q

The greater the distance you move the wedge…..

A

The greater the output force

58
Q

What is the MA of wedges?

A

Divide the length if the wedge by its greatest thickness(the longer/thinner the wedge is, the greater the MA)

59
Q

What is a screw?

A

A simple machine that consist if an inclined plane wrapped around a cylinder.,

60
Q

What does a screw apply when it is pushed?

A

A larger force through a short distance

61
Q

What does a screw applied when it is turned?

A

A small force over a large distance

62
Q

What is the MA of screws?,

A

Divide the length of screw by the height to which the load is lifted

63
Q

What is a wheel and axle?

A

A simple machine consisting of 2 circular objects if different sizes; the wheel is the largest of the 2 circular objects

64
Q

What is the MA of a wheel and axle?

A

The radius of the wheel divided by the radius of the axle.

65
Q

What results when a wheel is turned?

A

The mechanical advantage is greater than 1 because the radius of the wheel is larger than the radius of the axle.

66
Q

What is a pulley?

A

A simple machine that consists if a wheel over which a rope, chain, or wire passes.

67
Q

What is a fixed pulley?

A

Attached to something that doesn’t move

68
Q

What does a fixed pulley change?

A

The direction of the force

69
Q

Examples of fixed pulleys.

A

Elevators

70
Q

What is the MA of a fixed pulley and why?

A

1 because the size of the output force us the same as the size of the input force.

71
Q

What is a movable pulley?

A

Attached to an object being moved

72
Q

Examples of a movable pulley.

A

Construction crane

73
Q

What is the MA of a movable pulley and why?

A

2 because the pulley moves with the load as the load is lifted.

74
Q

Why does a movable pulley change?

A

It DOESN’T change the force’s direction. They increase force and distance over which the input force must be exerted.

75
Q

What is a block and tackle?

A

A fixed pulley and movable pulley used together

76
Q

What is MA of a block and tackle?

A

It depends on the number of rope segments because it multiples the input force.

77
Q

What is a compound machine?

A

Machines made of 2 or more simple machines

78
Q

What is the ME of compound machines and why?

A

Low because it has a lot of moving parts abs therefore more friction

79
Q

When does work occur?

A

When a force causes an object to move in the same direction of the force

Science (3 decks)

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