ninjakarl Posted November 24, 2005 Share Posted November 24, 2005 Today in Physics we were learning about different types of Energy (potential, kinetic etc) and we were shown the formula for finding out what the amount of Work is. You know, Force*Displacement*CosΘ and one of the examples for this was "a force is acting rightward and the object is being displaced leftward". I was just intruiged as to what an actual example of this would be in an everyday situation. My teacher didn't know and I would really like to know if you can think of anything. PS It was just meant to be an example to show us how to work it out. But I'm curious. Link to comment Share on other sites More sharing options...
_sphinx_ Posted November 24, 2005 Share Posted November 24, 2005 Today in Physics we were learning about different types of Energy (potential, kinetic etc) and we were shown the formula for finding out what the amount of Work is. You know, Force*Displacement*CosΘ and one of the examples for this was "a force is acting rightward and the object is being displaced leftward".I was just intruiged as to what an actual example of this would be in an everyday situation. My teacher didn't know and I would really like to know if you can think of anything. PS It was just meant to be an example to show us how to work it out. But I'm curious. 586847120[/snapback] "a force is acting rightward and the object is being displaced leftward" How is that physically possible? This goes against Newton's 2nd law which states that the rate of change in momentum is proportional to the net force acting on the object and takes place in the direction of the force. And what does this have to do with work? When you study work, you're simply told that work is a scaler quantity derived from displacment x force x cos the angle between the horizontal and the force (the last part is 1 if the force is horizontal since cos 0=1). If you push an object to the left with a force, it won't move right, will it? So my guess is: A. Your teacher is a certified moron B. Maybe you were dealing with multiple forces, for example: You're pushing a box with a force of 10N to the right, and I'm pushing it with a force of 20N to the left, in this case the resultant is 10N to the left, so in a way your stupid weird rule applies. There is a force acting to the right but its countered by a larger force opposing it. Link to comment Share on other sites More sharing options...
j.nudd Posted November 24, 2005 Share Posted November 24, 2005 "a force is acting rightward and the object is being displaced leftward"How is that physically possible? This goes against Newton's 2nd law which states that the rate of change in momentum is proportional to the net force acting on the object and takes place in the direction of the force. And what does this have to do with work? When you study work, you're simply told that work is a scaler quantity derived from displacment x force x cos the angle between the horizontal and the force (the last part is 1 if the force is horizontal since cos 0=1). If you push an object to the left with a force, it won't move right, will it? So my guess is: A. Your teacher is a certified moron B. Maybe you were dealing with multiple forces, for example: You're pushing a box with a force of 10N to the right, and I'm pushing it with a force of 20N to the left, in this case the resultant is 10N to the left, so in a way your stupid weird rule applies. There is a force acting to the right but its countered by a larger force opposing it. 586848039[/snapback] Either that or he/she just simply misstated. Link to comment Share on other sites More sharing options...
_sphinx_ Posted November 24, 2005 Share Posted November 24, 2005 Either that or he/she just simply misstated. 586848649[/snapback] yeah I guess so! That was preety rude, but the statment sounded so stupid to me Link to comment Share on other sites More sharing options...
ninjakarl Posted November 25, 2005 Author Share Posted November 25, 2005 http://www.glenbrook.k12.il.us/gbssci/phys...ergy/u5l1a.html This is the site that we were using, the teacher wasn't telling us this info per se but he couldn't think of anyway that it would work. The example is just designed to teach us how to work out Θ. Link to comment Share on other sites More sharing options...
Hitman2000 Posted November 25, 2005 Share Posted November 25, 2005 Edit* LOL I miss read your question I think. ANyways dont worry. Link to comment Share on other sites More sharing options...
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