imagine the rod balanced on a pin. you hit it 90 degrees, so you get maximum torque. the pin is still gonna feel a force. To cancel the force, you need to apply an opposite torque of identical magnitude and direction on the other side. then the force at the centre of the rod (on the pin head) will cancel out.
Or imagine the rod in space, no gravity. if you hit the extremity with a force, it wont rotate on the spot, but move forward as well. it will rotate on its centre if you apply the opposite torque on the other side.
Change in linear and rotational kinetic energy from force
Author
oliii, please re-read my posts. I understand what you''re saying and in fact we both agree that if you apply a torque to a free object it will both move and rotate. However, I''m curious why you and AP think that the linear acceleration is independent of where you hit the object. From my observation, if you hit a rod close to the center, it''ll move a lot and rotate a little. If you hit it at one of its ends, it''ll rotate a lot and move just slightly.
think of conservation of momentum... let''s say you''re sitting at one end of the rod and you shoot a bullet in a direction perpendicular to the r0 vector. the bullet has got some momentum, but overall momentum has to stay zero, so you and the rod have to move in the opposite direction.
i think your observation results from the fact that we are not used to do apply a certain force but rather to apply a force over a certain distance, with a certain acceleration. so when you hit the object nearer to the center of mass you apply a larger force to move your hand at some acceleration. when you hit it at the tip, the tip will rotate away and you don''t need that much force to keep the same acceleration of your hand.
i think your observation results from the fact that we are not used to do apply a certain force but rather to apply a force over a certain distance, with a certain acceleration. so when you hit the object nearer to the center of mass you apply a larger force to move your hand at some acceleration. when you hit it at the tip, the tip will rotate away and you don''t need that much force to keep the same acceleration of your hand.
Author
You guys might be right, and Ga''s explanation sounds valid. If this is really the truth, it''ll definitely simplify my life. Right now I''m busy alternating between physics and weather effects, but I''ll certainly give this a try. Thank you guys for your help.
from what I've seen here and in other posts, it seems there are two ways to split in force and torque: the one shown here, that uses the remaining force for torque, and others that use the full applied force for both force and torque.
so, which would be the correct ratio of force and torque when applying a force in a point of a body? That, if we want to conserve energy.
ah, well... seems it's being answered in another thread.
[edited by - vicviper on January 21, 2004 10:37:55 AM]
so, which would be the correct ratio of force and torque when applying a force in a point of a body? That, if we want to conserve energy.
ah, well... seems it's being answered in another thread.
[edited by - vicviper on January 21, 2004 10:37:55 AM]
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