Ch. 14

Question 1

A vertical force (does, does not) work on an object that is moving in a horizontal direction.

Answer 1

does not

Question 2

What is the SI unit of work?

Answer 2

joule

Question 3

What is rate of doing work?

Answer 3

Power

Question 4

How do you calculate power?

Answer 4

work/time

Question 5

What is the SI unit of power?

Answer 5

watt

Question 6

__________ is equal to one horsepower.

Answer 6

746 watts

Question 7

Describe what a machine is able to do.

Answer 7

makes work easier

Question 8

The work done by a machine is always less than the work done on a machine. Why?

Answer 8

friction

Question 9

What equation describes work input?

Answer 9

work input= input force x input distance

Question 10

The number of times that a machine increases an input forces is the _________________ of the machine.

Answer 10

mechanical advantage

Question 11

Greater input force is required to move an object along a ramp with a rough surface because a greater force is needed to overcome __________.

Answer 11

friction

Question 12

True or false?

A loading ramp with a rough surface has a greater mechanical advantage than one with a smooth surface.

Answer 12

false

Question 13

A machine’s ______________________ is the mechanical advantage in the absence of friction.

Answer 13

ideal mechanical advantage

Question 14

Why is the efficiency of a machine always less than 100% ?

Answer 14

there is always friction present

Question 15

Reducing friction __________ the efficiency of a machine.

Answer 15

increases

Question 16

List the six types of machines.

Answer 16

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

Question 17

List an example of a lever.

Answer 17

Using a screw driver to pry the lid off a paint can

Question 18

What is the fixed point that a lever rotates around?

Answer 18

fulcrum

Question 19

What characteristics levers as first-class, second-class, or third-class?

Answer 19

The position of the lever;
first- between input and output forces
third-between fulcrum and output force
\_\_
second-output force is between input force and fulcrum

Question 20

In science, work is done when a ________ acts of an object in the direction the object moves.

Answer 20

force

Question 21

The ideal mechanical advantage of an inclined plane is the _________________________ divided by________________.

Answer 21

distance along the incline plane,

its change in height

Question 22

Screws with threads that are close together have a greater _______________________.

Answer 22

ideal mechanical advantage

Question 23

What is a compound machine?

Answer 23

a combination of 2+ simple machines that operate together

Question 24

What are some examples of compound machines?

Answer 24

car,
washing machine,
watch

Question 25

What is the equation for efficiency?

Answer 25

work output
___________ x 100%
work input

Question 26

What is one way to determine output distance?

Answer 26

divide output work by output force

Question 27

Where is the input arm located?

Answer 27

an a lever, it is the distance between the fulcrum and the input force

Question 28

What machine increases as its thickness decreases relative to its length?

Answer 28

wedge

Question 29

Where is an input force exerted?

Answer 29

on a jack handle to lift a car

Question 30

What is the distance between the output force and the fulcrum?

Answer 30

output arm

Question 31

What SI unit is used to describe a lightbulb?

Answer 31

watt

Question 32

A slanted surface along which a force moves an object to a different elevation is called what?

Answer 32

inclined plane

Question 33

What is the equation for power?

Answer 33

Work/Time