Simple Machines Pretest

Question 1

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

Answer 1

Some of the work done is used to overcome friction.

Question 2

The unit for work is the…

Answer 2

Joule

Question 3

What is power?

Answer 3

How fast work is being done.

Question 4

The unit for power is the…

Answer 4

Watt

Question 5

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

Answer 5

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

Question 6

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?

Answer 6

Power

Question 7

What does a fixed pulley change?

Answer 7

The direction of the force

Question 8

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

Answer 8

Must decrease

Question 9

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

Answer 9

Moving the fulcrum closer to the load

Question 10

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

Answer 10

Reading a chapter for homework

Question 11

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

Answer 11

5000 J

Question 12

What action does more work on an object?

Answer 12

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

Question 13

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

Answer 13

10 W

Question 14

What is NOT a machine?

Answer 14

A glass

Question 15

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

Answer 15

10

Question 16

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….

Answer 16

The mechanical advantage is 1.

Question 17

Give an example of mechanical efficiency.

Answer 17

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

Question 18

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

Answer 18

Mechanical efficiency

Question 19

A ramp is an example of which simple machine?

Answer 19

Inclined plane m

Question 20

Your muscles and bones form a what?

Answer 20

Lever

Question 21

A jar lid is an example of a what?

Answer 21

Screw

Question 22

What is an example of a wheel and axle?

Answer 22

Doorknob

Question 23

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?

Answer 23

5

Question 24

With a fixed pulley, the input force is….

Answer 24

Is always equal to the output force

Question 25

A zipper is made of 3 what?

Answer 25

Wedges

Question 26

When you turn a screw, you apply a....

Answer 26

A small input force over a long distance

Question 27

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

Answer 27

Carrying a heavy suitcase down a long hallway

Question 28

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?

Answer 28

75%

Question 29

What is an example of a second class lever?

Answer 29

Wheelbarrow

Question 30

In a second class lever....

Answer 30

The load is between the fulcrum and the input force

Question 31

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

Answer 31

Third class lever

Question 32

A movable pulley...

Answer 32

Is attached to the load

Question 33

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

Answer 33

Distance

Question 34

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

Answer 34

Small force over a long distance

Question 35

A single pulley changes the .... An object

Answer 35

Direction of the input force on

Question 36

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?

Answer 36

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

Question 37

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?

Answer 37

1688 J

Question 38

What lever provides a mechanical advantage of less than 1?

Answer 38

Third class lever

Question 39

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

Answer 39

Joule

Question 40

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

Answer 40

Work input

Question 41

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

Answer 41

Mechanical efficiency

Question 42

What is a block and tackle an example of?

Answer 42

Compound machine

Question 43

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

Answer 43

Work

Question 44

What is also expressed as joules per second?

Answer 44

Watt

Question 45

What is work done by a machine called?

Answer 45

Work output

Question 46

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

Answer 46

Mechanical advantage

Question 47

What are machines consisting of 2 or more simple machines?

Answer 47

Compound machines

Question 48

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

Answer 48

Block and tackle

Question 49

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

Answer 49

Fixed pulley

Question 50

When is work being done?

Answer 50

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