Recent content by coffeebird

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    Basic Statics problem, forces on a Truss

    Homework Statement The truss is supported by a pin at A and roller at B. Determine the support reactions. Homework Equations sum of forces along y-axis, sum of forces along x-axis, sum of all torques The Attempt at a Solution Sum of x= Fax+ Fbx+ 5sin45=0 Sum of...
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    Electric Charge- why is the electron the negative

    that's what i was thinking...and people do that a lot, just stick with a convention for its own sake ( like not switching to the metric system in the US)
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    Electric Charge- why is the electron the negative

    Why wasn't the electron fixed with the 'positive' value? wouldn't that simplify a lot of issues with electronics problems, i mean, that way things wouldn't have to be all backwards. like, wherever the electrons go is becoming more negative, and whichever direction they are leaving is more...
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    Atwood's Machine with one side holding a variable mass

    in response- yes i know that i am looking for the rate of change- and yes i have taken calc classes, but i don't really see how that clarifies anything in this case, because- i guess I'm going to be super duper specific here - i don't know how to find that rate of change without first finding an...
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    Atwood's Machine with one side holding a variable mass

    so, m1= 1.30-.200t, but i don't know how to figure out an acceleration expression really
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    Very simple conversion problem

    okay, thank you : ) i guess I've just never really taken the time to write out proper conversions- i should probably start with that. so the unit you want goes on top, like meters/feet instead of feet/meters, right? and you mean 4.448 N per pound, i think?
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    Very simple conversion problem

    oh i see that's what you're saying, so what would a proper conversion look like step by step here?
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    Very simple conversion problem

    that's actually how they wrote the problem in my online statics thing- exactly like i did (except with the multiplication dot in the middle which i don't know how to make here)
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    Very simple conversion problem

    1/3.2808... but what's weirding me out is something i just noticed...i mean if there is that much force per foot, then shouldn't there be more force per meter?
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    Very simple conversion problem

    Homework Statement convert 20lb*ft to Newton*meters Homework Equations The Attempt at a Solution this is driving me nuts...so if 1lb= 4.448N, then we have 4.448*20 N*ft, and if there are 3.2808ft in one meter, then we should have 4.448*20*3.2808 N*m! so why is the answer...
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    Atwood's Machine with one side holding a variable mass

    Homework Statement Figure 5-47 shows Atwood's machine, in which two containers are connected by a cord (of negligible mass) passing over a frictionless pulley (also of negligible mass). At time t = 0, container 1 has mass 1.30 kg and container 2 has mass 2.80 kg, but container 1 is losing...
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    Tension in legs of an insect dangling upside down

    Homework Statement Some insects can walk below a thin rod (such as a twig) by hanging from it. Suppose that such an insect has mass m and hangs from a horizontal rod as shown in Fig. 5-35, with angle θ = 40°. Its six legs are all under the same tension, and the leg sections nearest the body...
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    Making a spool slide without rolling

    i think it would be 1, since if you are pulling it from the top, the string won't unravel (normally) and the spool won't have rotation just translation
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    Maximizing Sand Pulled: Angle & Weight

    Homework Statement An initially stationary box of sand is to be pulled across a floor by means of a cable in which the tension should not exceed 1220N. The coefficient of static friction between the box and the floor is 0.24. (a)What should be the angle between the cable and the horizontal...
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