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Quick physics question

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bdonn
Posts: 725 - Karma: 89
Can anybody help me understand why the net force on an object and the acceleration of the object are directly proportional?

+K to helpful answers.

Thanks NS.
Feb 8 2012 4:03PM
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.AR6rider.
Posts: 15976 - Karma: 8,799
Net force (F) = mass (m) x acceleration (a), so if you increase acceleration, force will be proportionally increased, since the mass of your object does not change.
Feb 8 2012 4:05PM
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[hamnuts]
Posts: 2356 - Karma: 439
I hate physics
Feb 8 2012 4:07PM
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HitTheJim
Posts: 787 - Karma: 399
khanacademy.org never have to ask questions on NS again!
Feb 8 2012 4:11PM
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lgski
Posts: 1832 - Karma: 2,291
There will never be such thing as a quick physics question on ns
Feb 8 2012 4:14PM
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Panchuk
Posts: 1610 - Karma: 356
Lol at religion. It's for the weak.
Feb 8 2012 4:23PM
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JzD.
Posts: 1615 - Karma: 153
If you increase one side of the equation you increase the other side too
Feb 8 2012 4:27PM
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chicken
Posts: 6843 - Karma: 2,121
Newtons second law says that the net force of an object is is equal to the time rate of change of its linear momentum.

in other words force is the time derivative of momentum. Momentum is mass*velocity. since this only applies to objects with constant mass, in the equation mass can be considered a constant and pulled out

so you end up with F=m(dv/dt).

since acceleration is the time derivative of velocity this works out to

F=ma

this is the most famous form of his second law and clearly shows that F is directly proportional to a. for example if mass is constant and you double the force, you will double the acceleration.
Feb 8 2012 4:36PM
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bdonn
Posts: 725 - Karma: 89
Fucking Brilliant. +k

Thank you.
Feb 8 2012 4:44PM
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Anathema
Posts: 21048 - Karma: 5,061

because women have smaller brains than men

Feb 8 2012 4:45PM
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katie.
Posts: 2833 - Karma: 874
this this this this this this this this this this this this this this this this this this this this
Feb 8 2012 4:48PM
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Bill.Nye
Posts: 4060 - Karma: 2,109
Click for larger image
Feb 8 2012 4:56PM
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fratskier69
Posts: 1868 - Karma: 1,271
net force is the total amount of things working on an object. if your acceleration is 0, the net force is 0 because the amount you have doing work on the object is the exact same amount acting against it ie. the force of a guy pushing a box at a constant speed is going to equal the amount of frictional force in the opposite direction.
if the thing starts to accelerate, it is because the forces acting on the object are imbalanced, causing its velocity to change.
the guy will start pushing harder on the box to speed it up, he needs to push harder than the amount of frictional force going in the opposite direction hes pushing.
maybe disregard that last examlple it makes it more confusing
Feb 8 2012 5:21PM
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