- Would Magneto get whiplash from Quicksilver?
- Analysis of Spider-Man’s webbed wings
- Modeling Captain America’s bouncing shield.
- Winter Soldier surviving a high jump
- How would Superman’s x-ray vision work?
- How does Ant Man’s shrinking power work?
- Physics of the new SHIELD Helicarrier.
- Could Superman punch someone into space?
- Not technically superhero, but this guy used a vacuum cleaner to be like Spider-Man
- Iron Man 3 carrying a chain of humans
- Could Iron Man survive a crash into the sand?
- Physics of The Hulk’s jump.
- Is Tobey Maguire really Spider-Man?
- Dr. Strange’s ideas about the nature of learning.
- Captain America’s rocket-powered kick.
- Could Black Widow scoop up Captain America’s shield?
- No one understands electromagnets in Spider-Man 2.
- Who is faster? Flash or Quicksilver?
- Should Spider-Man run or swing?
- The Physics of Spider-Man’s webs.
- Is Captain America’s shield a capacitor?
- How much does Captain America’s shield weigh?
- Avengers Homework.
- How much energy in Iron Fist’s punch?
- Finding the mass of Luke Cage.
- My interview about Geek Physics on Science Friday.
- Video analysis of Avengers jumping from a jeep.
- This is not the way tightropes work in Gotham.
- Modeling a ball bouncing off a wall.
- Maybe Quicksilver doesn’t run fast but instead warps time.
- The physics of scale – Ant Man runs wrong.
- Thor’s hammer has a weird center of mass.
- How hard does Iron Man hit The Hulk?
- Tony Stark doesn’t understand physics.
- Could Captain America jump from a plane without a parachute?
- How hard would it be for Iron Fist to catch a pole during a fall?
- Video analysis of Spider-Man jumping on a ferry.
- What should it look like (vs what it will look like in the movie) when Thor punches The Hulk?
- Would Wonder Woman recoil from blocking a bullet? How much power does she need to react in time?
- Spider-Man uses his web to stop a falling elevator. What is the spring constant of his webs?
- How should a superhero with super strength punch according to physics? From The Defenders.
- Does The Hulk get bigger in later movies?
- What does this physics question even mean in Spider-Man: Homecoming?
- Cyborg catches and then throws Aquaman in the Justice League trailer.
- Non spherical planets would be pretty difficult in Guardians of the Galaxy Vol 2. Why are planets spherical?
- Should Iron Man’s suit make two sparks when removing two charging cables? Hint: no.
- How much energy could Black Panther get from bullets hitting his suit?
- What would happen if this shrinking building in Ant-Man and the Wasp kept the same mass?
- What would happen to the rotation speed of a van wheel if the van got tiny? From Ant-Man and the Wasp.
- When Spider-Man is on top of a crashing plane, he should fall off in front of the plane, not behind.
- Video analysis of Aquaman jumping onto a submarine (from the Aquaman movie trailer).
- Estimation of Vision’s density in Captain America Civil War.
- How much power would Mysterio need to lift water to make that water monster in Spider-Man Far From Home?
- Superman might be strong, but he couldn’t pick up a building from the bottom. Physics says it would break.
- How fast is Quicksilver based on the scene from X-Men Apocalypse when he saves everyone from the exploding mansion? Uncertainty in the final speed included.
- A survey of flying superheroes in Avengers.
- Fixing the acceleration in a Tom Holland Spider-Man stunt.
- Video analysis of Captain America hitting Thanos with Mjolnir. Is momentum conserved? How much external force is required?
- Video analysis of Ravagers getting thrown up by Rocket – from Guardians of the Galaxy Vol. 2.
- Video analysis and a power estimation for Wonder Woman to hit this bullet out of the air (from WW84).
- Artificial gravity in a rocket – HBO Watchmen
- How fast would Wonder Woman need to spin her lasso to block bullets? (from Wonder Woman 1984)
- Iron Man and the Rocket Pendulum Fallacy.
- My WIRED Technique Critique video on super hero physics.
- How would Deadpool need to jump in order to crash through the roof of a moving vehicle?
- What is a state vector and how could you use it to find a hidden space lab in orbit? From Captain Marvel.
- How could Flash run faster than the speed of light and how would this make him time travel?
- What would happen if you jump with a wing suit but have two people? (From Falcon and the Winter Soldier)
- How do you calculate the required radiation shielding to enter the Hex in WandaVision?
- How difficult would it be for MJ to hold on to Spider-Man during a web swing (from the trailer to Spider-Man: No Way Home).
- How fast would Spider-Man have to jump (down) in order to catch up with a falling MJ?
- Peacemaker’s x-ray helmet. How could you see through stuff?
- How realistic is the celestial navigation scene in Moon Knight?
- An analysis of Thor’s chain battle-rope exercise from Thor: Love and Thunder (wave equation included).
- How much power does Batman’s ascender gun need for his escape in The Batman?
- How many peanut butter and jelly sandwiches does She-Hulk need to eat?
- The physics of flying superheroes. Also, how much power would it take for Namor to hover with his tiny wings?
- What kind of forces would Spider-Gwen need to stand on a wall like this?
- Video Analysis of the Guardians of the Galaxy running on a moon. How big is the moon?
- Which Spider-Man is stronger? Tobey Maguire in Spider-Man 2 or Tom Holland in Spider-Man: Homecoming?
- Terminal velocity and escape velocity for Magneto’s Asteroid M (X-Men 97).
- Could Captain America Survive a Punch from Red Hulk (from Captain America: Brave New World)
- Physics analysis of a falling building in the Superman trailer.
- Fantastic Four (First Steps): Could you throw someone (or someTHING) into space?
Page 20 of 27
Chapter 7 HW Part I
Chapter 7: 2, 3, 4, 5, 6, 8, 9, 11, 14, 15, 16, 20, 22, 23, 29
Some of these are easy – but they are good practice.
Final Reassessments
Just to be clear.
- Final reassessments are due on Monday July 20 – except for the last three standards.
- Collisions videos are due by July 22
- Videos for the last two standards are due BEFORE the final exam.
The Physics of Pedals
There are essentially two kinds of pedals: clips and flat (oh sure, there is clipless, but that is the same as clips).
So, which should you use? Let me start with clips.
Clips
Pros: These pedals are efficient. They let you push AND pull on a pedal. Cons: they aren’t hipster.
Flat
Pros: These pedals are hipster. Cons: they aren’t as efficient and your foot could slip off the pedal and cause a boo boo.
Torque produced by balls in Fantastic Contraption
The fun part about exploring the physics of [Fantastic Contraption](http://fantasticcontraption.com/) is coming up with new setups to test ideas. Torque is not too difficult to set up. Here is what I did:
In this setup, I have a “turning ball” with a wood stick attached to the side. I increased the length of the stick until the ball does not turn. At this point, the torque from the gravitational force on the stick is equal to the torque from the ball. I can use [Tracker Video Analysis](http://www.cabrillo.edu/~dbrown/tracker/) to find the lengths of the two wood sticks. The torque from each stick will be its gravitational weight times the perpendicular distance to the center of the turning ball.
In order to calculate the gravitational force, I need the mass of each “stick”. [From my previous post](http://blog.dotphys.net/2008/10/physics-of-fantastic-contraption-i/), I found that the mass density per length for sticks was
where mb is the mass of a ball and U is the diameter of a ball. I also need to find the horizontal distance from the center of the stick to the center of the ball. I will call the top stick 1 and the bottom 2. This gives:
Notice that stick 2 is connected at the same x-value as the ball, so I did not need to add the radius of the ball to its r value. Now I can calculate the total torque:
Although I do have an ok value for U in meters, I do not have a value for the mass of the ball, so no point in multiplying in the constant g. Anyway, let me test this. If this is true, how many balls could I hang right off the circle and lift? In that case, r would be 0.5 U (U is the diameter). So if the torque is around 3, I should be able to lift 6 balls (depending on the mass of string used). Let me try it.
I love it when a plan comes together. Actually, this was a little more than the weight of 6 balls, it also had the short length of water-sticks. But also, according to my calculation, this should not be able to lift 7 balls. Again, success.
Physics of Fantastic Contraption I
One of my students showed me this game, [Fantastic Contraption](http://fantasticcontraption.com/). The basic idea is to use a couple of different “machine” parts to build something that will move an object into a target area. Not a bad game. But what do I do when I look at a game? I think – hey! I wonder what kind of physics this “world” uses. This is very similar to [my analysis of the game Line Rider](http://blog.dotphys.net/2008/09/the-physics-of-linerider/) except completely different.
Fantastic Contraption gives the unique opportunity to build whatever you want. This is great for creating “experiments” in this world.
The first step is to “measure” some stuff. The game includes three types of “balls” and two types of connectors. The balls are:
- Clockwise rotating
- Counterclockwise rotating
- Non-driven
Connectors:
- wood lines – these can not pass through each other
- water lines – these can pass through each other, but not the ground
First question: Do the different balls have the same mass? This can be tested by creating a little “balance”
Fetch with Ruff Ruffman uses a laser to measure temperature?
I am sorry to point this out, but I can’t help it. My kids watch this show “Fetch with Ruff Ruffman”. It’s mostly an ok kids show. However, there was a problem. In one episode, some kids were in the desert and measuring temperature with (they said it several times and it was even a quiz question at the end) – a LASER. Here is the device they used:
This is an infrared thermometer with a LASER aiming system. The laser is only there to help you aim. The temperature is determined by measuring the infrared radiation from the object. You don’t even NEED the laser. Those ear thermometers work the same way, but they don’t have lasers.
I guess when a laser is involved, it just makes it so cool that it must be the most important thing. I am going to put a laser pointer on my computer – that way people can say “look, that computer runs on LASERS.”
A note about numerical calculations
[In a previous post, I talked about numerical calculations](http://blog.dotphys.net/2008/10/basics-numerical-calculations/). The basic idea is to use the momentum principle and the following “recipe”:
- Update the position of the particle
- Update the momentum of the particle
- Update the force on the particle
Looks great, right? Well, it mostly is great. I want to give a couple of pointers about the last step, update the force on the particle. How and when can you do this? Really, in numerical calculations, you will see two types of forces:
- Forces that you can calculate: That looks strange, but it’s true. Maybe you are thinking, can’t you calculate all the forces? – the answer is no. Yes, you can calculate the gravitational force and the electromagnetic force. Also, really all forces you are likely to see are one of those two. You can also calculate the force due to a spring(depends on position), the air resistance force (depends on velocity). These types of forces work well in the above numerical recipe.
- Forces that you CAN NOT calculate: These are all the other forces. Typically, these are forces of constraint. Suppose a block slides down a plane. Yes, you can calculate the force the plane exerts on the block, but it depends on things other than just the position of the block. The force the plane exerts on the block is such as to keep the block on the plane. You can not calculate this in the same way as the previous category of forces. Yes, technically the force the plane exerts on the block IS the electromagnetic force. If you want to calculate this force between all the atoms in the two objects, I encourage that.
So what does this all mean? This means that you can not use the above “recipe” for whatever you want. Sorry.
(I have a trick I will show you later)
Word Police: Use of the word pressure
I know I should just let go, but this is what makes me, me. I understand that there are terms in physics (like for instance ‘pressure’) that are used in all sorts of ways in common language. The problem is when someone tries to explain something scientifically and misuses a word. Pressure means something. It is the average force per area due to collisions of a gas or liquid on a surface. Really, you can see a good animation of this, I have a link and explanation when [I talked about MythBuster’s Lead Balloon](http://blog.dotphys.net/2008/09/mythbusters-how-small-could-a-lead-balloon-be/).
So, what is my problem? I was reading this interesting article on [Scientific American.com about solar refrigerators](http://www.sciam.com/article.cfm?id=solar-refrigeration). Here is a small quote:
*The key is the energy exchanged when liquids turn to vapor and vice versa—the process that cools you when you sweat. By far the most common approach, the one used by the refrigerator in your house, uses an electric motor to compress a refrigerant—say, Freon—turning it into liquid. When the pressure created by the compressor is released, the liquid evaporates, absorbing heat and lowering the temperature.*
“Pressure created by the compressor” isn’t too bad (although it might be interpreted by some that pressure is some substance). My biggest problem is the “When the pressure created by the compressor is released” part. How do you release pressure? Yes, you could allow the particles in the gas to stop colliding with the wall and thus “release” them. But aren’t you releasing the particles not the pressure?
I don’t mean to pick on this particular case because it’s not that bad. There are many other cases where the word pressure is used in a really incorrect manner.
On a side note, about the above article, I find cooling to an extremely interesting problem. It is funny how easy it is to heat something up, but so difficult to cool it off.
**PS:** I also don’t like how the article says “absorb heat”. This also implies that heat is a substance. I don’t really like the word “heat”.
Basics: Work Energy
**Pre Reqs:** [What is a Force](http://blog.dotphys.net/2008/09/basics-what-is-a-force/)
[Previously, I talked about the momentum principle](http://blog.dotphys.net/2008/10/basics-forces-and-the-momentum-principle/). Very useful and very fundamental idea. The other big (and useful) idea in introductory physics is the work-energy theorem. Really, with work-energy and momentum principle, you will be like a Jedi with a lightsaber and The Force – extremely powerful.
Well, what is work? What is energy? How are they related? In [another post, I talked about energy.](http://blog.dotphys.net/2008/10/what-is-energy/) I think it is interesting to look at how most textbooks define energy:
*Energy is the ability to do work*
This is really a stupid definition. Kind of circular logic, if you ask me. In the post I mentioned earlier, I claim there are two kinds of energy, particle energy and field energy. At low speeds (not near the speed of light), particle energy can be written as:
Where *m* is the mass of the particle, *c* is the speed of light. So, if you just look at a particle, that is it for the energy. Now, what about the “work” portion? Work is defined as:
Where *F* is the net force on the particle, ?r is the vector displacement of the particle. The “dot” in between F and ?r represents the “dot product” operation between vectors (also known as the scalar product). In a [previous post](http://blog.dotphys.net/2008/09/basics-vectors-and-vector-addition/) I showed that you could multiply a scalar quantity by a vector quantity. Here I need to do “something” with two vectors. You can’t multiply two vectors in the same sense that you multiply scalars. A general definition of the dot product for two vectors:
That looks a little more messy than I wanted, but it can not be helped. Really, it is not that complicated. The dot product is simply the projection of one vector on the other. Let me explain in terms of work.
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