# AP Physics 1: 1.1 Changes and Conservation Laws

AP Physics 1: 1.1 Changes and Conservation Laws. What is the speed of the other piece of wood?

AP Physics 1 | Changes and Conservation Laws |

Language | English Language |

Science Practice 2 | Using math appropriately |

### Transcript

two equally sized pieces that fly apart in opposite directions

One piece has a speed of three meters per second

what's the speed of the other And here the pendulum

answers to three six All right well luckily when we

were playing with wooden blocks they didn't spontaneously explode That

might have been pretty fun known Kind of cool to

watch All right now since we're dealing with two objects

moving in different directions one velocity will be positive and

the other will be negative They each start out it

zero since they're not moving And because these objects are

of equal mass and because their movement starts because of

the same force their momenta cancel each other out if

we adam together But we still get zero just like

how they started So let's get to the math We

have the two momenta which will label and wanted him

to linear momentum equals mass times velocity right Since the

total mo mentum equals zero we can subtract one moment

Um from the other two Get zero and then we

can plug in our numbers since the block split evenly

into the mass for each block is five kilograms and

we know one half's velocity is three meters a second

But when we do the math we see that the

other half's velocity is also three meters per second making

option b the right answer Now we did some math

to get there but we could have gotten the same

answer by just thinking about our old friend ike Yeah

Isaac newton Powdered wig in ala He's still the man

newton's third law states that for every action there is

an equal and opposite reaction Right We had a tattoo

Well that's what we put on our body So in

this explosion since one half takes off at three meters

per second wonder action the other piece has to do

the same just in the opposite direction But even if

we were to choose be right off the bat It's

Always good to know how the math works so we

can prove just how Smart We are right Sheldon bazinga

We were never able to prove our young genius with

blocks It turns out that it's pretty difficult to make

a particle collider with him but no worries though We 00:02:15.385 --> [endTime] still made sure there was a collision Sorry mom