ShmoopTube

00:00

Thank you We sneak and here's your shmoop du jour

00:05

brought to you by inertia We find inertia to be

00:09

its strongest on saturday morning All right during your study

00:12

group your study buddy turns to you and says inertial

00:15

and gravitational mass both have the same value They must

00:19

be the same thing right Well in order to prevent

00:23

him from failing the next physics quiz how should you

00:26

respond and hear the potential answers that All right we'll

00:34

get started Let's talk inertia way all know what gravity

00:38

is and no we're not talking about sandra bullock movie

00:40

although it was pretty cool and it did bank has

00:42

reconsider our dream of being an astronaut You may have

00:46

heard someone say a body at rest tends to stay

00:48

at rest and a body in motion tends to stay

00:51

in motion The person who first spoke these words was

00:54

yes sir isaac newton yet the same old guy who

00:57

took an apple to the head and figured out gravity

01:00

and he didn't say it exactly like that because they

01:02

spoken is funny way back then but that's the gist

01:05

of newton's first law of motion what this means is

01:08

that if you have a bowling ball sitting on a

01:10

table that ball isn't going to just start moving on

01:12

its own force needs to be applied to it to

01:15

make it move and once it's moving force needs to

01:18

be applied to make it stop moving or to make

01:21

it change direction that force can be friction or something

01:25

that can apply a direct force to stop the motion

01:28

So if we know what inertia is We can understand

01:30

inertial mass inertial mass is a measure of an object

01:34

tendency to resist change is in motion the mohr inertial

01:38

mass an object has the more it resists change like

01:41

your aunt who still thinks it's nineteen eighty six now

01:44

gravitational mass is calculated using an object gravitational weight but

01:49

don't confuse mass and weight They're not the same thing

01:53

mass doesn't change Sandra bullock has mass no matter where

01:58

she is but wait requires gravity that's why sandra can

02:02

be weightless in space she's not being pulled down by

02:05

the earth's gravitational force or by george clooney to calculate

02:08

an object gravitational mass We need to know the objects

02:12

weight and the force of gravity So when we put

02:15

all this knowledge together we see that the correct answer

02:18

is option A inertia refers to an objects resistance to

02:22

change while the gravitational mass is the mass calculated from

02:26

an object gravitational weight option b is wrong because the

02:30

values aren't different and objects inertial mass is the same

02:34

as its gravitational mass differences just in how they're measured

02:38

see gets it wrong because mass never refers to volumes

02:41

plus uses the definition of inertial master To find gravitational

02:47

and option d is wrong because the formula used to

02:49

calculate the types of masses is the same So if

02:52

inertial mass and gravitational masters equal to each other why

02:55

do we need to know the diff Well it's Because

02:58

they let us describe mass in different ways And that

03:00

lets us think about mass in different ways Being able

03:03

to think about things in different ways is always helpful

03:06

in physics or well any other branch of science and

03:08

know our inertial mass doesn't quadruple on those saturday mornings

03:12

Just

Full Transcript