How Do You Calculate the Unknown Charge in an Electrostatic Field?

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To calculate the unknown charge in an electrostatic field, the scenario involves a 60 nC charge and an unknown charge separated by 2.0 m, with the electric field strength being zero at a point 0.80 m from the unknown charge. The relevant equations include Coulomb's law and the electric field equations, specifically E = kq/r^2. The user is attempting to set up an equation based on these principles but is struggling to find the correct approach to relate the forces and fields from both charges. Clarification is sought on how to derive the electric field with two charges present and how to determine the force on a third charge in this context. Understanding the balance of electric fields from both charges is key to solving for the unknown charge.
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Homework Statement



An unknown charge and a charge of 60 nC are 2.0m apart. The electric field strength is zero at a point 0.80m from the unknown charge on a line connecting the two charges. Find the magnitutde of the unknown charge.

Homework Equations


q=F/E
F=kq1q1/r^2
E=kq/r^2

Coulomb constant: 8.99 x10^9


The Attempt at a Solution


I tried making an equation with the info given, but it doesn't seem like it's going to help me:
0=(8.99x10^9)(x)/(0.8)^2

i think i just need a push in the right direction
 
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anyone?
 
What is the equation of an electric field with 2 charges present?
 
JHamm said:
What is the equation of an electric field with 2 charges present?

uhh?
force?
 
If the system has 2 charges how do you find the force on a third charge at a point? :)
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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