chapter 9 test

Question 1

what is conserved?

Answer 1

mechanical energy is conserved when there is no net work done by external forces

Question 2

Kinetic energy equation

Answer 2

KE= 1/2 mv^2

Question 3

Gravitational Potential Energy equation

Answer 3

PE = mgh

Question 4

Spring potential energy equation

Answer 4

PE = 1/2 kx^2

Question 5

What does the term mechanical energy refer to?

Answer 5

the sum of a systems kinetic and potential energy

Question 6

positive work is…

Answer 6

is done by a force PARALLEL to an objects displacement

Question 7

negative work is …

Answer 7

is done by a force ANTIPARALLEL to an objects displacement

Question 8

when a force is acting perpendicular to an object displacement …

Answer 8

no work is done

Question 9

what type of quantity is work?

Answer 9

scalar because it can be positive or negative but it does not have a direction

Question 10

in a force vs. displacement graph what is the work?

Answer 10

the area underneath the graph

Question 11

power

Answer 11

the amount of work done in one second, or energy used in one second

Question 12

power equation

Answer 12

P = w/t

Question 13

unit for power

Answer 13

watts

Question 14

unit for work

Answer 14

joules

Question 15

what does the mechanical advantage of a simple machine tell you?

Answer 15

how much the input force is multipled to give you the output force

Question 16

whats the MA of a pulley?

Answer 16

the number of supporting tensions

Question 17

in an ideal simple machine the …

Answer 17

work in equals the work out

Question 18

the efficiency tells you…

Answer 18

how much energy is lost in any process for a simple machine

Question 19

what is the percent of efficiency in an ideal simple machine?

Answer 19

100%

Question 20

energy

Answer 20

the ability to do work

Question 21

potential energy

Answer 21

the energy of a position/shape/ or configuration

Question 22

elastic potential energy

Answer 22

potential energy that is stored in a spring or other elastic material

Question 23

what are examples of simple machines?

Answer 23

lever, pulley, wedge, inclined plane, wheel, axel, screw

Question 24

what does a simple machine do?

Answer 24

augments or multiples an applied force

Question 25

pulley

Answer 25

a simple machine that can change the direction and multiply an applied force

Question 26

efficiency equation

Answer 26

e = work out/ work in x 100%

Question 27

in most real-life simple machines…

Answer 27

some input work is lost due to friction so the work in does NOT equal the work out , and the efficiency is less than 100%