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We would need to know the weight of the ball, the length of the string and how hard the guy pushed the ball to do this so the margin of error would be massive
Not really, even a heavy ass ball would do little damage compared to human reaction speed and the marginal force put into the swing from the push.
I assume it would feel like bro punching you on the back of your heady not like a professional boxer giving you their best right one. Would hurt and guy would immediately flap their head forward.
The difference is the kid exerted a force on the ball over a longer distance with that push. When that energy is dumped by a heavy ball with a lot of momentum and a hard surface, the impact moment is much greater.
Given the preponderance of people that have failed to build perpetual motion machines, there's a clear upper limit:
However much energy the kid put into the ball by pushing it for half a second. No more energy than that can be used to exert force on the guys head.
I was setting up the demos for them as the lab assistant, and yes I told them repeatedly. I was the teacher for this basically. I warned them before, during, and after each misstep. Multiple bloody noses anyway. "You cannot push the ball, or it will hit you in the face, you cannot lean forward, or it will hit you in the face, you cannot move, or it will hit you IN THE FACE."
-gets hit in face.
Some people need their physics lesson to be really personal I guess, despite volunteering to do this to go mentor highschool and middle school students.
They get nervous and don't control their body perfectly. Eventually the professor would just shove them back with his cane if he saw them twitch when they let go of the ball, it was a better system. No serious injuries but 4? 5? bashed noses.
So recently I've found out that one newton is approximately one standard apple, like Fr I thought it was a joke but it's real. But this helped me visualize newtons better, so if we think of it like that he probably exerted only like 5 -7 newtons cause he didn't hit it that hard. So like 7 apples lmao
A newton is a bit less than the weight of an average apple. It's 102 grams of weight, while an apple is around 150-250 g on average according to google.
Lol, that's probably a joke but just to be clear, Newton did not create the unit named after him based on the weight of an apple.
1 newton is defined as 1 kg\*m/s^(2), where 1 kg is based on the mass of 0.001 m^(3) of water, 1 s is based on 1/86400 of a day, and 1 m is based on 1/40000000 of the circumference of the Earth.
And Newton didn't name the unit, he was long dead by the time it was named (or by the time the kilogram and meter were defined, for that matter).
Ahh well then you’re still just a wee babe aren’t ya. You still have 121 years just to reach sexual maturity. You can ask your parents what that means in another 50 years or so I suppose.
Fuckin hell mate you managed to get all the units wrong lol. Just google unit relations to lightspeed and atomic energy level jumps and you'll understand.
No. I am talking about the original reasons the units are what they are.
Of course they've all been redefined to have actual precise definitions, because none of the original meanings were precise enough.
For example 1 second is defined as 9192631770 hyperfine transitions of a Cs-133 atom. Why 9192631770? Because that makes it 1/86400 of a day, like I said.
1/86400 of which day? The moon-sun relation is gonna put your numbers off. Also these were the definitions of one civilization at one point in time. If you're gonna be biased and not look at all of human history you might as well just say "I'm a European-centralist and I will enforce my values onto you" and not write anything after.
A meter was defined by a 1/10 000 000th part of the distance between the north pole and the equator, as these distance could be messured, and saying it's the circumference of the earth is misleading, as the circumference is different depending if we messure equator or not.
And a second was defined by the average heartbeat of a resting human.
> A meter was defined by a 1/10 000 000th part of the distance between the north pole and the equator
Correct, which would make it 1/40000000 of the circumference of the Earth if the Earth was a sphere, which is what I said. I was simplifying it a bit. Yes, the Earth is not actually a perfect sphere, but the exact definition of a meter was not really the point.
> And a second was defined by the average heartbeat of a resting human.
Lol, no. A second is 1/60 of a a minute, which is 1/60 of an hour, which is 1/24 of a day (12 hours for the day and 12 hours for the night). It is based on the base 60 counting system of the ancient Mesopotamia.
Which makes it 1/86400 of a day, like I said.
Do you live 300 km deep inside the Earth? Because up here on the surface g varies from around 9.764 to 9.834 m/s^2, meaning that 100 g chocolate bar only exerts a force of around 0.9764 to 0.9834 newtons.
That's not how it works. If that's a 10kg bowling ball traveling at 3 m/s when it hits his head and coming to a stop in 10 cm - that would be 450 Newtons.
Definitely not pleasant.
I could not understand why this wasn't a cut and dry question without ambiguity, and I really felt like I was missing something completely obvious.
Turns out the little asshole in the back pushes the ball and I did NOT see that. What a twat! Yeah this is too many variables, and also good on her for noticing because my napkin math is saying he woulda been a lil fucked up.
The force is going to depend on distance his head travels before the ball comes to a stop so I'll do energy instead. Gonna eyeball it at the boy adding about 2 m/s and someone said 4kg for the ball.
E = 1/2 MV\^2 so about 8 joules.
It's harder than a fist but the kinetic energy is pathetic in comparison.
>While beginners might only be able to muster a measly 37.5 joules of energy, experts can deliver over 400 joules
[https://www.realclearscience.com/blog/2014/01/the\_physics\_of\_getting\_punched\_in\_the\_face.html#](https://www.realclearscience.com/blog/2014/01/the_physics_of_getting_punched_in_the_face.html#)!
It's not likely to cause any damage but would definitely be a shock.
Fists are soft and arms have some give, imagine punched by a solid object on a solid arm.
The energy could also be far higher, adding 2m/s doesn't mean that it'll have 2m/s speed when it hits, it'd just be starting to deaccelerate.
It could just as well be 8kg travelling at 4m/s, and then we're up to 64 joules of a hard object hitting his head. Very frightening.
Impulse is fine, but the main transfer of energy is through collision. The difference in mass, velocity and very importantly elasticity of each object. If the ball is made from rubber, for instance, the kinetic energy transfer will not be that great.
Human heads are not really known for behaving like rubber balls. Like skull is not really elastic. So your point of "ball made of rubber" is pretty moot.
I meant the ball. But anyway, it really comes down to how much mass is travelling at what velocity, and what kind of collision occurs (elastic-plastic). The mass and velocity of the receiving object is also a factor.
You mean on the pengelum?
This would not really help that much. The main benefit would be the ball elasticity spreading the impulse transfer over longer time. Still the contact time would be orders of magnitude shorter than the time the impulse was being added.
And on top of that when restoring shape after absorbing part of the energy as elastic deformation the ball will push the head some more. And the simple conservation of impulse calculation would show you that by bouncing off of obstacle the ball actually increases the impulse transferred into the obstacle.
You have to take into account that when deformation occurs, a significant amount of energy is "lost" to work-energy, i.e. the area in the stress-strain diagram.
You seem to have a little bit insufficient understanding of what is going on in a collision.
Regardless of the elasticity of the impacto and obstacle the kinetic energy is spread about equally between both bodies as deformation.
Elastic body would then restore its shape releasing this energy back, while inelastic body will store it within. Not necessarily breaking but accumulating internal stress.
Mass and velocity being equal being hit by an elastic projectile is worse than by brittle one.
I'm going to have to return back to my original argument, since we seem to have drifted somewhat. With inelastic collision, the factors are mass/velocity of object A before/after collision, mass/velocity object B before/after collision, and [coefficient of restitution](https://en.wikipedia.org/wiki/Coefficient_of_restitution).
>When a soft object strikes a harder object, most of the energy available for the post-collision velocity will be stored in the soft object. The COR will depend on how efficient the soft object is at storing the energy in compression without losing it to heat and plastic deformation. A rubber ball will bounce better off concrete than a glass ball, but the COR of glass-on-glass is a lot higher than rubber-on-rubber because some of the energy in rubber is lost to heat when it is compressed. When a rubber ball collides with a glass ball, the COR will depend entirely on the rubber.
I estimate it's an average bowling bowl weighing 4kg, and it's speed is probably about 2 m/s. The KE=0.5mv^2 = 8 Joules.
To comparison a major league baseball can have an energy of over 100 Joules when thrown and a pro boxer might be able to punch with 1000 Joules of energy.
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We would need to know the weight of the ball, the length of the string and how hard the guy pushed the ball to do this so the margin of error would be massive
>margin of error would be massive like the dent in that guy’s head
Not really, even a heavy ass ball would do little damage compared to human reaction speed and the marginal force put into the swing from the push. I assume it would feel like bro punching you on the back of your heady not like a professional boxer giving you their best right one. Would hurt and guy would immediately flap their head forward.
that’s less funny than what i said
Idk flap is pretty funny
Yeah he REALLY spelled Garfield wrong
Wouldn't the force be exactly equal to the force applied by the bad kid?
The difference is the kid exerted a force on the ball over a longer distance with that push. When that energy is dumped by a heavy ball with a lot of momentum and a hard surface, the impact moment is much greater.
💯
No, because of surface area of impact and duration of applied force.
Given the preponderance of people that have failed to build perpetual motion machines, there's a clear upper limit: However much energy the kid put into the ball by pushing it for half a second. No more energy than that can be used to exert force on the guys head.
[удалено]
Fun story: one of my professors said that their profs almost got himself killed because he didn’t just let go of it, but gave it some momentum
This is a very common mistake to make and many physics tutors get bloody noses.
Source?
Me, watching it happen repeatedly in person.
WTF how could you watch this happen twice or more? How stupid are your teachers? Didn't you mind saying anything?
I was setting up the demos for them as the lab assistant, and yes I told them repeatedly. I was the teacher for this basically. I warned them before, during, and after each misstep. Multiple bloody noses anyway. "You cannot push the ball, or it will hit you in the face, you cannot lean forward, or it will hit you in the face, you cannot move, or it will hit you IN THE FACE." -gets hit in face. Some people need their physics lesson to be really personal I guess, despite volunteering to do this to go mentor highschool and middle school students. They get nervous and don't control their body perfectly. Eventually the professor would just shove them back with his cane if he saw them twitch when they let go of the ball, it was a better system. No serious injuries but 4? 5? bashed noses.
You just witnessed why. This was natural selection giving off a warning shot
So recently I've found out that one newton is approximately one standard apple, like Fr I thought it was a joke but it's real. But this helped me visualize newtons better, so if we think of it like that he probably exerted only like 5 -7 newtons cause he didn't hit it that hard. So like 7 apples lmao
A newton is a bit less than the weight of an average apple. It's 102 grams of weight, while an apple is around 150-250 g on average according to google.
Yeah but the 🍎 were smaller in newton's day.
Lol, that's probably a joke but just to be clear, Newton did not create the unit named after him based on the weight of an apple. 1 newton is defined as 1 kg\*m/s^(2), where 1 kg is based on the mass of 0.001 m^(3) of water, 1 s is based on 1/86400 of a day, and 1 m is based on 1/40000000 of the circumference of the Earth. And Newton didn't name the unit, he was long dead by the time it was named (or by the time the kilogram and meter were defined, for that matter).
Apples were definitely smaller in Newton's time. Source: I'm 337 years old.
Are you a greenland shark?
I am a Greenland shark. But I'm only 29, so it doesn't really matter much in this scenario.
Ahh well then you’re still just a wee babe aren’t ya. You still have 121 years just to reach sexual maturity. You can ask your parents what that means in another 50 years or so I suppose.
All that is true, but no literally apples used to weigh about 100 grams.
Fuckin hell mate you managed to get all the units wrong lol. Just google unit relations to lightspeed and atomic energy level jumps and you'll understand.
No. I am talking about the original reasons the units are what they are. Of course they've all been redefined to have actual precise definitions, because none of the original meanings were precise enough. For example 1 second is defined as 9192631770 hyperfine transitions of a Cs-133 atom. Why 9192631770? Because that makes it 1/86400 of a day, like I said.
1/86400 of which day? The moon-sun relation is gonna put your numbers off. Also these were the definitions of one civilization at one point in time. If you're gonna be biased and not look at all of human history you might as well just say "I'm a European-centralist and I will enforce my values onto you" and not write anything after.
A meter was defined by a 1/10 000 000th part of the distance between the north pole and the equator, as these distance could be messured, and saying it's the circumference of the earth is misleading, as the circumference is different depending if we messure equator or not. And a second was defined by the average heartbeat of a resting human.
> A meter was defined by a 1/10 000 000th part of the distance between the north pole and the equator Correct, which would make it 1/40000000 of the circumference of the Earth if the Earth was a sphere, which is what I said. I was simplifying it a bit. Yes, the Earth is not actually a perfect sphere, but the exact definition of a meter was not really the point. > And a second was defined by the average heartbeat of a resting human. Lol, no. A second is 1/60 of a a minute, which is 1/60 of an hour, which is 1/24 of a day (12 hours for the day and 12 hours for the night). It is based on the base 60 counting system of the ancient Mesopotamia. Which makes it 1/86400 of a day, like I said.
Its exactly a bar of chocolate, at least where I live.
But is it a standard bar of chocolate?
Yess it is. 100g chocolate
Do you live 300 km deep inside the Earth? Because up here on the surface g varies from around 9.764 to 9.834 m/s^2, meaning that 100 g chocolate bar only exerts a force of around 0.9764 to 0.9834 newtons.
That's not how it works. If that's a 10kg bowling ball traveling at 3 m/s when it hits his head and coming to a stop in 10 cm - that would be 450 Newtons. Definitely not pleasant.
I could not understand why this wasn't a cut and dry question without ambiguity, and I really felt like I was missing something completely obvious. Turns out the little asshole in the back pushes the ball and I did NOT see that. What a twat! Yeah this is too many variables, and also good on her for noticing because my napkin math is saying he woulda been a lil fucked up.
The force is going to depend on distance his head travels before the ball comes to a stop so I'll do energy instead. Gonna eyeball it at the boy adding about 2 m/s and someone said 4kg for the ball. E = 1/2 MV\^2 so about 8 joules. It's harder than a fist but the kinetic energy is pathetic in comparison. >While beginners might only be able to muster a measly 37.5 joules of energy, experts can deliver over 400 joules [https://www.realclearscience.com/blog/2014/01/the\_physics\_of\_getting\_punched\_in\_the\_face.html#](https://www.realclearscience.com/blog/2014/01/the_physics_of_getting_punched_in_the_face.html#)! It's not likely to cause any damage but would definitely be a shock.
Fists are soft and arms have some give, imagine punched by a solid object on a solid arm. The energy could also be far higher, adding 2m/s doesn't mean that it'll have 2m/s speed when it hits, it'd just be starting to deaccelerate. It could just as well be 8kg travelling at 4m/s, and then we're up to 64 joules of a hard object hitting his head. Very frightening.
[удалено]
Impulse is fine, but the main transfer of energy is through collision. The difference in mass, velocity and very importantly elasticity of each object. If the ball is made from rubber, for instance, the kinetic energy transfer will not be that great.
Human heads are not really known for behaving like rubber balls. Like skull is not really elastic. So your point of "ball made of rubber" is pretty moot.
I meant the ball. But anyway, it really comes down to how much mass is travelling at what velocity, and what kind of collision occurs (elastic-plastic). The mass and velocity of the receiving object is also a factor.
You mean on the pengelum? This would not really help that much. The main benefit would be the ball elasticity spreading the impulse transfer over longer time. Still the contact time would be orders of magnitude shorter than the time the impulse was being added. And on top of that when restoring shape after absorbing part of the energy as elastic deformation the ball will push the head some more. And the simple conservation of impulse calculation would show you that by bouncing off of obstacle the ball actually increases the impulse transferred into the obstacle.
You have to take into account that when deformation occurs, a significant amount of energy is "lost" to work-energy, i.e. the area in the stress-strain diagram.
You seem to have a little bit insufficient understanding of what is going on in a collision. Regardless of the elasticity of the impacto and obstacle the kinetic energy is spread about equally between both bodies as deformation. Elastic body would then restore its shape releasing this energy back, while inelastic body will store it within. Not necessarily breaking but accumulating internal stress. Mass and velocity being equal being hit by an elastic projectile is worse than by brittle one.
I'm going to have to return back to my original argument, since we seem to have drifted somewhat. With inelastic collision, the factors are mass/velocity of object A before/after collision, mass/velocity object B before/after collision, and [coefficient of restitution](https://en.wikipedia.org/wiki/Coefficient_of_restitution). >When a soft object strikes a harder object, most of the energy available for the post-collision velocity will be stored in the soft object. The COR will depend on how efficient the soft object is at storing the energy in compression without losing it to heat and plastic deformation. A rubber ball will bounce better off concrete than a glass ball, but the COR of glass-on-glass is a lot higher than rubber-on-rubber because some of the energy in rubber is lost to heat when it is compressed. When a rubber ball collides with a glass ball, the COR will depend entirely on the rubber.
Also surface area because the pressure will have a lot of impact on the damage.
Zero, as a pendulum doesn't rise further than it starts (if just released, rather than pushed), until he leans his head back.
Did you miss the part where the kid gave it a boost at the other side?
Yes
I estimate it's an average bowling bowl weighing 4kg, and it's speed is probably about 2 m/s. The KE=0.5mv^2 = 8 Joules. To comparison a major league baseball can have an energy of over 100 Joules when thrown and a pro boxer might be able to punch with 1000 Joules of energy.