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Science > Simple Machines Pretest > Flashcards

Simple Machines Pretest Flashcards

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1
Q

The output force for a machine is always less than work input because….

A

Some of the work done is used to overcome friction.

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2
Q

The unit for work is the…

A

Joule

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3
Q

What is power?

A

How fast work is being done.

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4
Q

The unit for power is the…

A

Watt

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5
Q

Name a situation where a person is doing work on an object.

A

A school crossing guard raises a stop sign that weighs 10 N.

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6
Q

Juan and Anita each lift an identical stack of books the same distance onto a table, but Anita does the job twice as fast. Therefore, her actions involve twice as much what?

A

Power

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7
Q

What does a fixed pulley change?

A

The direction of the force

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8
Q

When a machine increases the size of the force exerted, the distance through which the force is exerted….

A

Must decrease

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9
Q

What would increase the mechanical advantage of a first class lever?

A

Moving the fulcrum closer to the load

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10
Q

What is not an example of doing work according to the scientific definition?

A

Reading a chapter for homework

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11
Q

A man applies a force of 500 N to push a truck 10 m down the street. How much work has been done?

A

5000 J

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12
Q

What action does more work on an object?

A

Lifting a 90 N box 2 m off up the floor. ( look for a higher work value )

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13
Q

If you do 50 J of work in 5 seconds, your power is….

A

10 W

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14
Q

What is NOT a machine?

A

A glass

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15
Q

You apply 200 N to a machine and the machine applies 2000 N to an object. What is the mechanical advantage?

A

10

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16
Q

You apply 10 N to a machine and the machine applies 10 N to move another object. Since the input force is equal to the output force….

A

The mechanical advantage is 1.

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17
Q

Give an example of mechanical efficiency.

A

95% (any number less than 100 but not less than 0 in a precent form)

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18
Q

Getting regular oil changes for your car improves the car’s….

A

Mechanical efficiency

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19
Q

A ramp is an example of which simple machine?

A

Inclined plane m

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20
Q

Your muscles and bones form a what?

A

Lever

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21
Q

A jar lid is an example of a what?

A

Screw

22
Q

What is an example of a wheel and axle?

A

Doorknob

23
Q

What is the mechanical advantage of a wheel and axle where the wheel’s radius is 10 cm and the axle’s radius is 2 cm?

A

5

24
Q

With a fixed pulley, the input force is….

A

Is always equal to the output force

25
Q

A zipper is made of 3 what?

A

Wedges

26
Q

When you turn a screw, you apply a….

A

A small input force over a long distance

27
Q

What is NOT an example of doing work on a suitcase?

A

Carrying a heavy suitcase down a long hallway

28
Q

If a machine has a work input of 8 N and gives a work output of 6 N, what is the machine’s mechanical efficiency?

A

75%

29
Q

What is an example of a second class lever?

A

Wheelbarrow

30
Q

In a second class lever….

A

The load is between the fulcrum and the input force

31
Q

Hammering a nail into wood is an example of using a….

A

Third class lever

32
Q

A movable pulley…

A

Is attached to the load

33
Q

When a machine changes the size of a force, the ….. Must also change.

A

Distance

34
Q

To do the same amount of work on an object, a large force is applied over a short distance can be exchanged by what?

A

Small force over a long distance

35
Q

A single pulley changes the …. An object

A

Direction of the input force on

36
Q

In 1994, a 3000 kg pancake was cooked, and flipped, in Manchester, England. Suppose you had a giant spatula that you could use as a lever to flip this pancake. Where could you best position the fulcrum and the pancake in order to get the greatest mechanical advantage?

A

Place the fulcrum close to the pancake as in a first class lever.

37
Q

The largest turtle ever caught in the U. S. weighed about 844 N. How much work would be done to lift this turtle slowly 2 m from the surface of the water onto the deck of a research ship?

A

1688 J

38
Q

What lever provides a mechanical advantage of less than 1?

A

Third class lever

39
Q

What is the SI unit equivalent to 1 N times m?

A

Joule

40
Q

What is the work you do on a machine such as turning a screwdriver called?

A

Work input

41
Q

What is always less than 100% for a machine because of friction?

A

Mechanical efficiency

42
Q

What is a block and tackle an example of?

A

Compound machine

43
Q

What is done on an object when a force exerted on the object causes it to move in the direction of the force?

A

Work

44
Q

What is also expressed as joules per second?

A

Watt

45
Q

What is work done by a machine called?

A

Work output

46
Q

What of a machine indicates how many times the machine multiplies force by comparing the input with the output force?

A

Mechanical advantage

47
Q

What are machines consisting of 2 or more simple machines?

A

Compound machines

48
Q

A pulley system in which a fixed and a movable pulley are used together

A

Block and tackle

49
Q

What is a pulley attached to something that does NOT move?

A

Fixed pulley

50
Q

When is work being done?

A

When you exert a force that moves an object in the direction of the force.

Science (3 decks)

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