chapter 3

Question 1

Work

Answer 1

the transfer of energy that occurs when a force is applied over a distance

Question 2

Work Equation

Answer 2

work (in joules) = force (in newtons) x distance (in meters)
W = Fd

Question 3

Power

Answer 3

rate at which work is done

Question 4

Power Equation

Answer 4

power (in watts) = work (in joules)/time (in seconds)
P = w/t

Question 5

Mechanical advantage

Answer 5

the ratio of a machine’s output force produced to the input force applied

Question 6

Mechanical advantage

Answer 6

output force (in newtons)/ input force (in newtons)
MA = F out / F in

Question 7

Efficiency

Answer 7

a machine is the ratio of the output work to the input work

Question 8

Efficiency (in %)

Answer 8

output work (in joules)/ input work (in joules) x 100%
Efficiency = W out/ W in x 100%

Question 9

Simple machines

Answer 9

do work using only one movement

Question 10

Lever

Answer 10

a simple machine made up of a bar that pivots, or rotates, about a fixed point

Question 11

Fulcrum

Answer 11

The point about which a lever pivots

Question 12

Wheels and axle

Answer 12

is an axle attached to the center of a wheel and both rotate together

Question 13

Ideal mechanical advantage

Answer 13

radius of wheel (in meters)/ radius of axle (in meters)
IMA = R wheel/ R axle

Question 14

Inclined plane

Answer 14

a flat, sloped surface, or a ramp
Ideal mechanical advantage

Question 15

Inclined Plane equation

Answer 15

length of inclined plane (in meters)/ height of inclined plane (in meters)
IMA = l/h

Question 16

Wedge

Answer 16

A sloped surface that moves

Question 17

Screw

Answer 17

an inclined plane wrapped around a cylinder

Question 18

Pulley

Answer 18

a simple machine that is a grooved wheel with a rope or a cable wrapped around it

Question 19

what must you know to calculate work

Answer 19

force and distance

Question 20

what happens when work is done on an object

Answer 20

the energy of the object increases

Question 21

What is the rate at which work is done

Answer 21

power

Question 22

what three ways can a machine make work easier in three ways

Answer 22

changing the size of a force, changing the distance of the force acts, or changing the direction of a force

Question 23

what is the mechanical advantage of a machine

Answer 23

the ratio of the output force to the input force

Question 24

Because the friction, the output work done by a machine is always_______than the input work of the machine

Answer 24

less

Question 25

What does friction between moving parts do

Answer 25

converts some of the input work into thermal energy and decreases the efficiency of the machine

Question 26

A simple machine does work using

Answer 26

only one movement

Question 27

The ideal mechanical advantage of simple machines is calculated using

Answer 27

simple formulas

Question 28

A compound machine is made of what

Answer 28

two or more simple machines that operate together

Question 29

when is work done on an object

Answer 29

when the object moves in the direction of the applied force

Question 30

what happens when work is done on an object

Answer 30

energy is transferred to the object

Question 31

how is the efficiency of a machine increase

Answer 31

when a lubricant coats moving parts

Question 32

six simple machines are

Answer 32

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