Jump to content

All Activity

This stream auto-updates     

  1. Today
  2. AP Physics 1 Momentum Supplemental Problem 7b

    Hi Maren, The positive/negative impulse implies direction. By Newton's 3rd Law, if the block applies an impulse to the ball of 10 N*s, the ball must apply an impulse back to the block of 10 N*s in the opposite direction, therefore the block experiences an impulse of -10 N*s. Since its mass is 0.5 kg, its change in velocity must be -20 m/s. If it's going 20 m/s in the positive direction, and experiences a change of -20 m/s, that leaves it at 0. Think of it this way. As the block travels to the right (positive direction) and hits the ball, it pushes the ball to the right, so the ball receives a positive impulse. Likewise, the ball must push the block to the left, so the block receives a negative impulse. This is not a realistic problem, but from a theoretical standpoint it walks you through some of the key points of momentum. The area under a force-time curve gives you the impulse (calculated in part A). In part B, you use the impulse-momentum theorem to find the change in the ball's velocity. In part C, you use Newton's 3rd Law coupled with the impulse momentum theorem to find the velocity of the block after the collision. And in part D, you utilize the definition of a elastic vs. inelastic collisions.
  3. Yesterday
  4. Last week
  5. I am confused about problem number seven part b in this pdf. http://aplusphysics.com/ap1/Problems/AP1 Momentum.pdf I read the given answer, and I am still confused. I don't know how you are supposed to get 0 m/s for the velocity of the block. Why do you use negative impulse for the block when you use positive impulse for the sphere? When do you use negative impulse? Why don't you use the mass of the entire system, which would be the block and the ball? This has to do with it being elastic/inelastic, but I don't know how you can tell from an impulse graph. Help??
  6. Name: Deriving Escape Velocity of Planet Earth Category: Circular Motion & Gravity Date Added: 2018-02-18 Submitter: Flipping Physics Escape velocity is defined and illustrated. The escape velocity of planet Earth is derived. Want Lecture Notes? This is an AP Physics 1 topic. Content Times: 0:07 Translating the problem 0:42 Defining escape velocity 1:43 Conservation of mechanical energy 3:22 Initial and final mechanical energies 5:38 The escape velocity of planet Earth 6:19 Relating this to binding energy Multilingual? Please help translate Flipping Physics videos! Previous Video: Deriving the Binding Energy of a Planet Please support me on Patreon! Thank you to Dan Burns, Jonathan Everett, Christopher Becke, Sawdog, and Scott Carter for being my Quality Control Team for this video. Thank you to Youssef Nasr for transcribing the English subtitles of this video. Deriving Escape Velocity of Planet Earth
  7. Escape velocity is defined and illustrated. The escape velocity of planet Earth is derived. Want Lecture Notes? This is an AP Physics 1 topic. Content Times: 0:07 Translating the problem 0:42 Defining escape velocity 1:43 Conservation of mechanical energy 3:22 Initial and final mechanical energies 5:38 The escape velocity of planet Earth 6:19 Relating this to binding energy Multilingual? Please help translate Flipping Physics videos! Previous Video: Deriving the Binding Energy of a Planet Please support me on Patreon! Thank you to Dan Burns, Jonathan Everett, Christopher Becke, Sawdog, and Scott Carter for being my Quality Control Team for this video. Thank you to Youssef Nasr for transcribing the English subtitles of this video.
  8. Earlier
  9. Superionic Ice

    Water and ice molecules on earth have a distinct molecular structure that gives it the properties that it has; however, under different surrounding pressures, the molecular structure can change, resulting in the formation of superionic water. Superionic water differs from the ice/water you and I know so well. "Regular" ice has molecules that form a V shape with two hydrogen atoms and one oxygen atom. As pressure increases, these atoms get squeezed into different shapes. A property that superionic ice has is that it is a conductor of electricity; however, unlike most conductors, the current is carried by positively charged ions instead of negatively charged electrons. This substance was just a theoretical idea until recently when the University of Rochester's OMEGA laser tested the theory and was successful in creating superionic ice. They knew this was a success because the molecules were able to conduct electricity. Due to the opaque color of the molecules when electricity was ran through it, it was determined that it was, in fact superionic. If it had a shiny look to it, the researchers would have known that it couldn't of been superinoinc because that would mean that negative electrons were carrying the current. The pressures that were applied to the ice by the laser were almost 2 million times the atmospheric pressure of earth. This is the amount of pressure that planets Neptune and Uranus have.
  10. Failure is Necessary for Growth

    Time for a little mental health rant… We all want our children to be the best they can be, to feel good about themselves, and to reach their potential. Part of this process, however, involves learning to fail productively — understanding and experiencing what it’s like to fall short, knowing that sick feeling in your gut is uncomfortable but necessary, and disliking that feeling enough to do something about it and try again. I sure hope I’m wrong, but I feel like many of the changes I’m seeing in the way we as a society deal with children is sending the wrong message. These changes are made with the best of intentions — we don’t want anyone to feel left out, and we don’t want children to experience the pain of failure — but we as adults who know better need to recognize that these uncomfortable experiences are important to building up confidence, self esteem, and independence. Kudos that aren’t truly earned don’t teach a child to work hard, they teach a child that showing up is enough. I’m not saying little ones need to be beaten into submission, or that I should always crush my kid in a game of Connect Four — but I do think they need to learn that they can’t win every time, otherwise there’s no impetus to improve. They won’t always get picked first to be on a team, there will be days when they are left out of activities their friends get to experience, and there will be events when they’ll leave the field and not be the winner of the event. This is OK, it’s an opportunity learn the importance of giving your all, of preparing as fully as possible, and the value of sportsmanship, both on top and at the bottom of the podium. I think it’s also important for our kids to understand what makes us proud and what is disappointing. Sportsmanship is important, but it’s also important to realize that decisions leading up to events contribute to the success or failure of that event. As a teacher I observe students who work their tail off and struggle for a middling grade… and I try to instill a sense of pride in that work and that grade. I also have students who slack off and are naturally talented enough to earn A’s. I try to explain to these students that they are not reaching their potential, and I don’t find that acceptable. There will be times when our kids may try and try and try, but never reach the level of success that they desire. Recently I’ve dealt with repeated instances of academic dishonesty, from students who are taking shortcuts in their classes, and aren’t recognizing the connection between their integrity, work ethic, and results. True self esteem and confidence comes from understanding that you can go to bed every night with no regrets, having given your all, not from an external source such as a trophy or a piece of paper with a letter on it. And not meeting every goal just tells you that you’ve set aggressive goals. If you reach every one of your goals, you’re not reaching high enough. I don’t think it’s valuable to get into specifics, as you can find “opportunity for improvement” in so many of the things we do and say with our kids, from the toddlers to the older young-at-heart — in our homes, in our schools, and in our activities. But I would ask, if some of this does resonate with you, to take a step back and look at what changes you can make, or ways you can support and reinforce those who are instilling these old-fashioned values. And don’t be afraid to speak up every now and then and question what you see occurring. Just because someone thinks it’ll make everyone feel better, doesn’t mean it’s a good idea. And just like our mothers taught us, popular opinion doesn’t mean it’s the right opinion. Remember the old adage “if all your friends jumped off a bridge would you jump off too?” It’s time for all of us to start thinking for ourselves. The post Failure is Necessary for Growth appeared first on Physics In Flux.
  11. Singing Glasses

    Last weekend at an honors interview at Roberts, I got to take a look in some of their physics labs. they had some fun things set up for us to check out. One thing was in a section called "physics and music". Sounds perfect for me, right? They had a bunch of wine glasses filled with different amounts of water. When you dipped your finger in some water and rubbed it around the edge of the glass, a specific note could be heard. However, if your finger isn't wet, it doesn't work. Why? Turns out, it is because there is too much friction between the finger and the glass when the finger is dry. When the finger is wet, there is minimal friction, which allows the glass to vibrate, which produces the note. The amount of water in the glass determines how high or low pitched the note is. If you try this experiment, try placing a ping pong ball in the glass. The ping pong ball will make the vibrations visible because it will move on top of the water as the glass vibrates.
  12. The symbol of invention, ingenuity and enlightenment, the light bulb is perhaps a most pivotal invention in the course of human history. The advent of the lamp made it possible to render the dark of night and shed a lambency on the way to the future! Truly, the light bulb is all we could ever ask for. They say 'teach a man to fish and he will not have light but teach a man of the fluorescent lamp and he will have that light!' but in all seriousness let us illuminate the obscure nature of the fluorescent light! Different varieties of the fluorescent light may use cathodes of tungsten that release heat and electrons while being electrically heated itself and this provides the energy needed to produce the 'lighting' effects.As I have said once before in my previous blog about atomic energy levels and their associated light spectra, it was a consummation of this knowledge that we make an effective application of phenomena. A electric current passes through the mercury gas, exciting its electrons and emits high energy light as they descend to ground level. That energetic lights strikes a phosphorescent or fluorescent salt, the white powder inside the glass tube, which emits light itself. A mixture of noble gases which ionize as a result of the heat being generated by the cathodes, allowing sufficient current to excite the gaseous mercury. All these components make for an expensive assembly and their complexities make them a challenge to manufacture which results in a unattractive price. However they are known to be many times more efficient than their incandescent cousins, saving money and electricity in the long term. Fluorescent bulbs are also a environment friendly choice, while containing mercury, the construction of incandescent lamps actually produce more mercury waste.
  13. Name: Deriving the Binding Energy of a Planet Category: Circular Motion & Gravity Date Added: 2018-02-12 Submitter: Flipping Physics Binding energy of a planet is defined and derived. Want Lecture Notes? This is an AP Physics 1 topic. Content Times: 0:21 Defining binding energy 0:48 Proving change in gravitational potential energy equals work done by force applied 3:03 Universal gravitational potential energy 3:39 The binding energy of a planet 5:16 An alternate way of solving this problem Multilingual? Please help translate Flipping Physics videos! Previous Video: Universal Gravitational Potential Energy Introduction Please support me on Patreon! Thank you to Jonathan Everett, Christopher Becke, Sawdog, and Scott Carter for being my Quality Control Team for this video. Thank you to Youssef Nasr for transcribing the English subtitles of this video. Deriving the Binding Energy of a Planet
  14. Binding energy of a planet is defined and derived. Want Lecture Notes? This is an AP Physics 1 topic. Content Times: 0:21 Defining binding energy 0:48 Proving change in gravitational potential energy equals work done by force applied 3:03 Universal gravitational potential energy 3:39 The binding energy of a planet 5:16 An alternate way of solving this problem Next Video: Deriving Escape Velocity of Planet Earth Multilingual? Please help translate Flipping Physics videos! Previous Video: Universal Gravitational Potential Energy Introduction Please support me on Patreon! Thank you to Jonathan Everett, Christopher Becke, Sawdog, and Scott Carter for being my Quality Control Team for this video. Thank you to Youssef Nasr for transcribing the English subtitles of this video.
  15. Escape Velocity and Black Holes

    Every massive object in space has an escape velocity. Escape velocity is the minimum velocity an object must have in order to escape the gravitational strength of a particular planet or any large body in space. The earths escape velocity is about 11.2 km/s. This means that an object must travel 11.2 km/s to escape its orbit around the earth. Reaching this velocity is a very big challenge when dealing with space travel. The more mass a body has, the more gravitational attraction it has; therefore, the escape velocity becomes faster. A black hole's escape velocity is so high that nothing can escape its gravitational pull; not even light. That is why its call a "black" hole: there is no light coming out of it so you can't see in it. A black holes escape velocity must be greater than 300,000 km/s (the speed of light). How can in object have this must mass to generate this much gravitation? When a star reaches the end of its life, some of them collapse all the way down to a single point, maintaining it's mass. This means that it becomes infinitely dense. Our sun does not have the potential to eventually become a black hole because it is too small. Stars that become black holes are 20 times the mass of the sun.
  16. Luge

    I have never heard of the word "luge" until today when looking at events in the Winter Olympics. Luge is a sport where there is a rider on a sled that is sliding down ice feet first. The objective is to get down the track in the fastest amount of time. They often look like this while racing... The rider has to fight air resistance to get down the track as fast as possible. They start at the top of an ramp and then have to go around turns until they reach the finish line. Although this may not seem like a dangerous sport, riders can reach speeds of 95 mph or more. In the 2010 Winter Olympics, rider Nodar Kumaritashvili died in a practice run hours before the opening ceremony. Because of his high speed, he flew off his sled into the air and hit a metal pole. Due to his death, track designers for the 2014 Winter Olympics designed a track that went uphill in some areas which would force riders into slower speeds. Riders rely on gravity and proper turn times to reach the finish line the fastest. Until next time, RK
  17. What makes an Element?

    My favorite bond is the bond between friends!
  18. The Leyden Jar

    @BrandyBoy72 Yo I think I messed this one up so bad. It was nice knowing you, sorry I could not help you more. My only regret is not being a good person. Farewell, walk free...
  19. Physics Behind a Fly Fishing Cast

    Wow they turned RPG fishing into a real thing!
  20. Bend it like Beckham

    @krdavis18 You are the physics duchess!
  21. Viscosity

    You prefer Waffles over pancakes?
  22. The Leyden Jar

    As the nature of electricity was investigated into the eighteenth century through static electricity and to a certain extent the triboelectric effect, it was only natural that the discovery of electric charge and capacitance would follow. Independently, three scientists named Ewald Georg von Kleist, Pieter van Musschenbroek and Andreas Cunaeus. A machine of sorts, one that would supply charge through triboelectric electric effect by friction, would transfer the charge to two conducting, metallic foils that act as electrodes, generated a disparity in charge and electric potential. The plates are on the inside and the outside of a glass jar, the glass acting as a semiconductor and because of the electric field, electric potential is created across the glass. This glass would "hold" the charge in a sense. You see, the mystery at the time was the exact nature of electricity. Many believe electricity was some invisible fluid-like thing. Electricity could only be observed from sparks, repulsion and other natural phenomenon so at the time humans were working with an incomplete theory of electricity. However the later two scientists Pieter van Musschenbroek and Andreas Cunaeus identified the mechanism of action that we now know today. The idea is that the inside and outside surfaces of the glass became charged by the foils, equally and oppositely, causing a potential difference across the glass itself as a dielectric. The discovery of capacitance has lead to the advent of a variety of useful modern technologies like computers and circuitry which I hope to investigate at a later time.
  23. Viscosity

    I wonder what causes this? IMFs or maybe solution saturation. Anyways waffles are way more convenient than pancakes. Waffles stay crisp while pancakes absorb the syrup and become ooze-like in consistency.
  24. Recycling Rockets

    NASA wanted their space shuttle program to be completely reusable. Sadly, due to budget cuts, only the actual shuttle was reusable, and the boosters were ditched. On the other hand, Space X wanted to save as much money and as many resources as they could. On the right is a picture of Space X's Falcon Heavy rocket, designed to, as the name suggests, lift a large payload into space, and on the plus side, at a much cheaper cost than before. On the left is a clip of the two "small" side boosters landing simultaneously after the Falcon Heavy's test flight yesterday. Sadly, the main booster missed the landing barge in the ocean and was lost. By saving the boosters, we can save a lot of money and time that would be spent into making new ones for every launch. Also, if you didn't know, the Falcon Heavy was carrying Elon Musk's personal car, a Tesla Roadster. They put a dummy in a space suit in the driver's seat, put "Don't Panic" on the display, and the radio, even though you can't hear it, is playing "Space Oddity." Or "Rocket Man." I don't remember. If you want to check out more, here's the link to SpaceX's livestream, which also has the videos of the test flight, and a simulation of the test flight which are pretty cool. http://www.spacex.com/webcast
  25. SpaceX

    He's not. Like a cult, Elon Musk makes false promises to followers and he gets grants from our government for doing nothing. Render this illusion and seek what is yours, the truth.
  26. SpaceX

    Elon Musk is a god!
  27. Bend it like Beckham

    As I said in my first blog post, I love playing soccer in my free time, so I thought I would finally explore some of the physics behind a really cool technique in soccer of bending the ball. Players often use this skill when taking free kicks to put a spin on the ball and curve their shot into the goal. This technique is famously used my David Beckham and the video below highlights one of the most famous moments when he used this technique to win a match in the World Cup. It's incredible to see the curved path that the ball takes when you look at the footage of the goal head on. Players like Beckham are able to accomplish this by imparting a spin to the ball. When you kick a soccer ball with the inside of your foot and you hit the ball in its center of gravity, it is going to move off in a straight line. However, if you kick the ball with the front of your foot and kick it slightly off-center and with your ankle bent into an "L" shape, the ball will curve in flight. This is because the applied force on the ball acts as a torque which gives the ball a spin. This spinning in the air then causes the ball to be laterally deflected in flight in what is known as the Magnus effect which causes the "bending" motion of the ball in the air. You can see this represented in the image below: As you can see its pretty neat to learn about the physics behind this cool soccer technique and learn something new about the game!
  28. Name: Universal Gravitational Potential Energy Introduction Category: Circular Motion & Gravity Date Added: 2018-02-05 Submitter: Flipping Physics Universal Gravitational Potential Energy is introduced and graphed. It is compared to the force of gravity. And the “zero line” is defined. Want Lecture Notes? This is an AP Physics 1 topic. Content Times: 0:11 “Normal” gravitational potential energy 1:33 Gravitational fields 2:22 Universal Gravitational Potential Energy Equation 3:07 Comparing gravitational potential energy to force of gravity 4:12 Graphing Universal Gravitational Potential Energy 5:35 The “zero line” for universal gravitational potential energy 6:05 Can universal gravitational potential energy ever be positive? 6:49 Gravitational potential energy at the surface of the Earth 7:57 Three things to be careful of. Multilingual? Please help translate Flipping Physics videos! Previous Video: Gravitational Field Introduction Please support me on Patreon! Thank you to Dan Burns, Jonathan Everett, Christopher Becke, Sawdog, and Scott Carter for being my Quality Control Team for this video. Thank you to Youssef Nasr for transcribing the English subtitles of this video. Universal Gravitational Potential Energy Introduction
  29. Universal Gravitational Potential Energy is introduced and graphed. It is compared to the force of gravity. And the “zero line” is defined. Want Lecture Notes? This is an AP Physics 1 topic. Content Times: 0:11 “Normal” gravitational potential energy 1:33 Gravitational fields 2:22 Universal Gravitational Potential Energy Equation 3:07 Comparing gravitational potential energy to force of gravity 4:12 Graphing Universal Gravitational Potential Energy 5:35 The “zero line” for universal gravitational potential energy 6:05 Can universal gravitational potential energy ever be positive? 6:49 Gravitational potential energy at the surface of the Earth 7:57 Three things to be careful of. Next Video: Deriving the Binding Energy of a Planet Multilingual? Please help translate Flipping Physics videos! Previous Video: Gravitational Field Introduction Please support me on Patreon! Thank you to Dan Burns, Jonathan Everett, Christopher Becke, Sawdog, and Scott Carter for being my Quality Control Team for this video. Thank you to Youssef Nasr for transcribing the English subtitles of this video.
  1. Load more activity

Terms of Use

The pages of APlusPhysics.com, Physics in Action podcasts, and other online media at this site are made available as a service to physics students, instructors, and others. Their use is encouraged and is free of charge. Teachers who wish to use materials either in a classroom demonstration format or as part of an interactive activity/lesson are granted permission (and encouraged) to do so. Linking to information on this site is allowed and encouraged, but content from APlusPhysics may not be made available elsewhere on the Internet without the author's written permission.

Copyright Notice

APlusPhysics.com, Silly Beagle Productions and Physics In Action materials are copyright protected and the author restricts their use to online usage through a live internet connection. Any downloading of files to other storage devices (hard drives, web servers, school servers, CDs, etc.) with the exception of Physics In Action podcast episodes is prohibited. The use of images, text and animations in other projects (including non-profit endeavors) is also prohibited. Requests for permission to use such material on other projects may be submitted in writing to info@aplusphysics.com. Licensing of the content of APlusPhysics.com for other uses may be considered in the future.

×