Pretty tough physics questions...please help

[jdpaul14]

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Hey guys,

Didn't know how to solve these, wondering if you guys could help.

1) Find the total electric charge of 1.5 kg of (a) electrons and (b) protons

2) A point charge q = -0.35 nC is fixed at the origin. Where must a proton be placed in order for the electric force acting on it to be exactly opposite to its weight? (y axis is vertical and x axis is horizontal)

3) A 5.0 uC charge experiences a 0.44 N force in the positive y direction. If this charge is replaced with a -2.7 uC charge, what fore will it experience?


Thanks in advance,

 

[kabirm]

1) Find the total electric charge of 1.5 kg of (a) electrons and (b) protons

just take 1.5/ (molecular mass of electron or proton)= number of electrons or protons * the charge on each= total electric charge

http://physics.bu.edu/~duffy/PY106/Charge.html

this will give you information regarding weights nad charges

2)dont understand ur wording

3) A 5.0 uC charge experiences a 0.44 N force in the positive y direction. If this charge is replaced with a -2.7 uC charge, what fore will it experience?

F= (k)(Q1)(Q2)/R^2= .44 N

Or F = qE=.44

I would use number 2 if it is permited ... so .44/5 uC (remember units here) =E

after you find E multiply it by -2.7 uC charge

I suggest first drawing a Cartesian plane and placing ur vectors of the force and charge

Remember negative force is attraction, while positive force is repulsion..so with a 5 uC charge you know the other charge is positive since u have positive force

 

[kabirm]

also remember if your dealing with kg ..divide by kg of weight for electrons not grams

 

[jdpaul14]

So, for #1 I would do:

(1.5/9.11x10^-31)(1.6x10^-19) and this would be my answer?

 

[kabirm]

nope you forgot the negative sign because electrons carry negative charge, but otherwise that is correct

 

[Seraph 84]

What test prep resource did these questions come from?

 

[0Complications]

What test prep resource did these questions come from?

I'm going to guess the one that involves a professor and a homework assignment...

 

[capn jazz]

Yea, I've never seen any questions like this.

 

[Seraph 84]

I'm going to guess the one that involves a professor and a homework assignment...

Haha, my thoughts exactly. Don't post here for homework questions, SDN has a policy on that.