Chapter 4: Work and Energy

Question 1

force applied through a distance; measure of energy transfer that occurs when an object is moved over a distance by an external force

Answer 1

work

Question 2

a device that changes the force or increases the motion from work

Answer 2

machine

Question 3

a machine that does work with only one movement of the machine

Answer 3

simple machine

Question 4

six types of simple machines:

Answer 4

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

Question 5

a combination of two or more simple machines

Answer 5

compound machine

Question 6

the ratio of output work to input work

Answer 6

efficiency

Question 7

the ratio of the output force to input force

Answer 7

mechanical advantage

Question 8

the ability to cause change

Answer 8

energy

Question 9

energy that is due to chemical bonds

Answer 9

chemical potential energy

Question 10

energy that is stored by compressing or stretching an object

Answer 10

elastic potential energy

Question 11

energy due to motion

Answer 11

kinetic energy

Question 12

energy that is stored due to the interactions between objects

Answer 12

potential energy

Question 13

anything around which you can imagine a boundary; can be a single object or a group of objects

Answer 13

system

Question 14

energy that is due to the gravitational forces between objects

Answer 14

gravitational potential energy

Question 15

states that energy cannot be created or destroyed; energy can only be converted from one form to another or transferred from one place to another

Answer 15

law of conservation of energy

Question 16

the sum of the kinetic energy and potential energy of the objects in a system

Answer 16

mechanical energy

Question 17

the rate at which energy is converted

Answer 17

power

Question 18

the equation for work is:

Answer 18

work (J) = applied force (N) * distance (m)

W = Fd

Question 19

the equation to find efficiency is:

Answer 19

efficiency (%) = output work (J) /input work (J) * 100

e = Wout/Win* 100

Question 20

what is the equation to find mechanical advantage

Answer 20

mechanical advantage = output force (N) / input force (N)

MA = Fout/Fin

Question 21

the equation to find kinetic energy:

Answer 21

kinetic energy (J) = 1/2 mass (kg) * [speed (in m/s)]^2

KE = 1/2mv^2

Question 22

the equation to find gravitational potential energy:

Answer 22

gravitational potential energy (J) = mass (kg) * gravity (N/kg) * height (m)

GPE = mgh

Question 23

power equation:

Answer 23

Power (watts) = Energy (J) / time (s)

P = E/t

Question 24

Machines make doing work ______ or ________ by ______________________.

Answer 24

easier; faster; changing the force needed to do the work

Question 25

3 possible functions of a machine:

Answer 25

increase speed, change direction of a force, or increase force

Question 26

relative to the input work on a machine, the output work from that machine is…

Answer 26

never as great

Question 27

forms of energy

Answer 27

mechanical, electrical, chemical, thermal, radiant

Question 28

different forms of potential energy:

Answer 28

elastic, chemical, and gravitational

Question 29

energy cannot be created or destroyed. what can it do/what can happen to it?

Answer 29

energy can be transferred between forms

Question 30

mechanical energy is the sum of…

Answer 30

all of the potential energies and kinetic energies of all the objects in a system