# AP Physics 2: 1.1 Changes and Conservation Laws

AP Physics 2: 1.1 Changes and Conservation Laws. Which of the following statements are true?

AP | AP Physics 2 |

AP Physics 2 | Changes and Conservation Laws |

Language | English Language |

Science Practice 7 | Relating knowledge across scales, concepts, and representations |

Test Prep | AP Physics 2 |

### Transcript

water spouting from the bottom hole or the pressure at both holes is equal and

here the potential answers... Okay so hail doesn't usually [Man with a white beard and hair in the clouds]

move horizontally but like we said this is at freak hail storm, so freaky that it

doesn't have to obey the laws of physics but that doesn't mean we get the same [Car driving down a road in a hailstorm and person whistles stop!]

luxury no we have to obey the law and right now we're dealing with officer

Bernoulli. Bernoulli's principle is an extension of the law of conservation of

energy it states that at any two points in a flowing fluid the total energy is [example of Bernoulli's principle]

the same well the equation is the pressure energy plus the potential

energy plus the kinetic energy at one point equals that at the second point

and because we're dealing with fluids instead of using M for mass, the equation

uses row for the mass per volume now in this question the pressure at each hole

is the same it's just the pressure from the atmosphere since the pipe is in [Arrows pointing to a pipe]

providing pressure at the holes, so the second statement is true well to

determine if the first statement is also true let's look at the Bernoulli [Man jumps and drags the Bernoulli principle down]

principle again yikes we're not going to lie it's a little intimidating but we

can make it a little easier on the eye on the brain first of all since the [Man staring at Bernoulli's principle with googly eyes]

pressure at both points is the same we can take out the P sub 1 and the P sub 2

now we have an equation that just deals with potential and kinetic energy or if

we think about this scenario we can set the height of the lower hole to zero and [liquid flowing out of two holes in a pipe]

state that the higher hole is at a certain height of H after all we don't

really care what happens further down the pipe we'll let whoever has to fix

this lousy piece of metal worry about that so let's say that the sub 1 part of [Man screams while repairing the pipe]

the equation is for the lower hole and the sub 2 part for the upper one well if

the potential energy of the lower hole is 0 the equation now looks like

this looking at this equation we can see that the kinetic energy at the lower

point has to be higher at the higher point some of the energy is still stored

as potential energy so the kinetic energy at the higher point has to be

lower than it is lower down the pipe and that means that the velocity at the

higher point can't be greater than at the lower point so the first statement in

the question is false and that means the correct answer is B. careful if the

weather turns ugly as if rain and wind and lightning aren't enough sometimes [Man walking in a hailstorm]

mother nature decides to throw falling objects at our heads it's like payback

for that one time we forgot to recycle a soda can [Soda can hits man's head as he crosses the road]