AP Physics 2: 1.3 Fields in Space

AP Physics 2: 1.3 Fields in Space. How long will it take PANCAKE to reach the plate?

AP Physics 2Fields in Space
LanguageEnglish Language
Science Practice 2Using math appropriately

Transcript

00:24

to blast off back to earth when it realizes it's

00:26

booster rocket is broken A rescue satellite finally appears ten

00:31

kilometers above the surface The satellite has a charged plate

00:35

that creates a uniform electric field of magnitude tend of

00:38

the sixth newton cool ums pancake has a mass of

00:41

one hundred kilograms It charges itself with six hundred micro

00:46

coolant and stands directly under the plate Acceleration due to

00:50

gravity on mars is four meters per second squared Well

00:54

the figure displays the situation with pancake treated as a

00:57

point charge How long will it take pancake to reach

01:00

the plate And here the angel answers any second All

01:04

right we'd love to go to mars but let's talk

01:06

about failing rockets and lack of food and water really

01:09

doesn't make it sound all that much fun But if

01:11

we were to get stuck maybe a rescue satellite come

01:14

save us In this case the charge from the satellite

01:16

is pulling up on our little pancake and the martian

01:19

gravity is pulling it down Thie first thing we have

01:21

to do is figure out the forces being applied to

01:24

the martian explorer will the upward force Being applied by

01:27

the satellite equals the charge times The magnitude of the

01:29

electric field and the force of gravity pulling pancake down

01:33

equals mass times gravity Well the electric force is positive

01:37

and the gravitational force is negative Since they're acting in

01:40

opposite directions we'll figure out the net force We subtract

01:44

the gravitational force from the electric force But hold on

01:47

a second Just finding the force isn't going to tell

01:49

us how long this trip takes for that We need

01:52

to find pancakes Acceleration acceleration equals force divided by mass

01:57

so we can put our net force equation over master

02:00

to find the acceleration Now we can plug in the

02:03

numbers find the acceleration So here we go Six hundred

02:05

micro columns times ten to the sixth minus one hundred

02:08

kilograms times four meters per second Squared over one hundred

02:11

kilograms When we boil it all down gives us an

02:15

acceleration of two meters per second squared Alright we found

02:19

the acceleration We still have to figure out how long

02:21

it takes for pancake to reach the satellite and head

02:24

for home We know the acceleration is two meters per

02:27

second squared We know the distance of the satellite is

02:30

ten kilometers or ten thousand meters and we know that

02:33

we're dealing with kinnah matics at this point All right

02:36

we need an equation that involves time acceleration and distance

02:40

Well the one to go with is the distance or

02:43

displacement equation Distance equal starting velocity times time plus one

02:48

half acceleration times times square that'll do with rick The

02:54

starting velocity is zero so we can knock the first

02:56

part of the equation out Now We know that ten

02:59

thousand meters equals one half two meters per second squared

03:03

times times square well solving for time were able to

03:06

see that it takes pancake one hundred seconds to reach

03:09

the sweet embrace of the rescue satellite The right answer

03:12

is the houston pancake is headed home Goes down sticking