things can be more complex than they first appear.
I used to hate such questions where if you really looked at the problem there was more to it than what you had been told in class.
Some many times I was at odds with the teachers with such issues..they called me disruptive and not interested when in fact I was more interested and concerned with truth than anyone else in class.
Hmmm. 4Gs coming out of the hand. I don't think so with a juggling action. A quick calculation shows that if the pin is in the hand for one second (perhaps a reasonable time frame), the pin will exit the hand at over 140 km/hr.
Regards
Steven
You failed to take into account that the pin arrives at a speed and exits at the same speed but in the opposite direction. If the pin arrives in the hand at 70km/h and is accelerated in the opposite direction and leaves the hand at 70km/h, then you have a differential speed of 140km/h, but only a throwing speed of 70km/h, which is reasonable.
-70 +140 = +70
I would imagine the pin would be in the hand for a shorter period than this, and I only used 1 second in the hand as an example because it made the underlying math more easy to understand.
An exact acceleration equivalent to 4G's (upwards) is the only acceleration acceptible and possible for the juggler to juggle 5 pins with a smooth motion.
things can be more complex than they first appear.
I used to hate such questions where if you really looked at the problem there was more to it than what you had been told in class.
Some many times I was at odds with the teachers with such issues..they called me disruptive and not interested when in fact I was more interested and concerned with truth than anyone else in class.
alex
The moral to the story for me in school was "teachers can be idiots that don't know jack apart from what is written in the book infront of them". I had some fantastic teachers in school, & I had some real dunces. I consistantly scored distinctions in the school science competitions however, and I have a fair amount of faith in my own ability to disseminate a problem and work out an answer.
Well Steven (with respect to all those wonderful teachers who I think are great doing what they do) teachers never have left school and therefore somewhat insulated from some of lifes realities.
But heck ex teachers always made the best sales people which I attribute to management of groups of children...management of buyer lists and listing prospects is very similar because you need to understand each individual and what makes them tick.
I employed ex teachers readily because they mostly were great performers in sales.
AND Steven your ability is very evident you always provide very well considered views... just dont fall into the teachers trap of believing everything you read...particulary about dark matter
Well Steven (with respect to all those wonderful teachers who I think are great doing what they do) teachers never have left school and therefore somewhat insulated from some of lifes realities
If I was the teacher I would explain it as gravitational potential energy being equivalent to the kinetic energy of the pin depending on how far it was thrown up! The impulse needed F delta t gives you the change in momentum and hence the energy and then you can calculate a time averaged force. As a time average the juggler weighs his 47kg + 10kg of pins.
You failed to take into account that the pin arrives at a speed and exits at the same speed but in the opposite direction. If the pin arrives in the hand at 70km/h and is accelerated in the opposite direction and leaves the hand at 70km/h, then you have a differential speed of 140km/h, but only a throwing speed of 70km/h, which is reasonable.
-70 +140 = +70
That makes no sense at all. The juggler catches the pin. The physics of catching an object involves bringing the object to rest while the hand is subjected to a short term impulse force. If the object isn't brought to rest you have a collision or hitting action.
If in fact the pin drops into the juggler's hand at 70 km/hr under 1g acceleration, then the juggler has thrown the pin to a height of over 19 metres. Yet another improbable scenario for juggling.
That makes no sense at all. The juggler catches the pin. The physics of catching an object involves bringing the object to rest while the hand is subjected to a short term impulse force. If the object isn't brought to rest you have a collision or hitting action.
Steven
If in fact the pin drops into the juggler's hand at 70 km/hr under 1g acceleration, then the juggler has thrown the pin to a height of over 19 metres. Yet another improbable scenario for juggling.
Steven
So change the 1 second throw time ffs. It was just used as an example to explain the freaking maths
If I was the teacher I would explain it as gravitational potential energy being equivalent to the kinetic energy of the pin depending on how far it was thrown up! The impulse needed F delta t gives you the change in momentum and hence the energy and then you can calculate a time averaged force. As a time average the juggler weighs his 47kg + 10kg of pins.
Bert
You are stating the obvious but the point of the discussion is to select conditions that are within the physical capabilities of the juggler to prove the point.
AND Steven your ability is very evident you always provide very well considered views... just dont fall into the teachers trap of believing everything you read...particulary about dark matter
alex
Alex,
It's the scientist coming out of me wanting to perform a test to verify the assertion.
Are you trying to say a good juggler could do it? If you integrate the force over the time no matter how gradual, the momentum change still is the same. This is a waste of my time. The answer is self evident to anyone who knows 12th year physics.
Are you trying to say a good juggler could do it? If you integrate the force over the time no matter how gradual, the momentum change still is the same. This is a waste of my time. The answer is self evident to anyone who knows 12th year physics.
Bert
The juggler cannot cross the bridge. Have I made that clear enough?
Should I also make it clear that the solution be realistic that factors in the physical limitations imposed by the juggler?
In mathematical terms it's known as a boundary value condition.
Thanks for wasting my time having to explain this to you.
.
... just dont fall into the teachers trap of believing everything you read...particulary about dark matter
