What is the magnitude of the electric field

AI Thread Summary
The discussion revolves around calculating the magnitude of the electric field generated by a cat with a charge of -54.1 µC at a distance of 4.01 m. The correct formula to use is E = kQ/r², where k is the Coulomb's constant. Initial calculations led to confusion, with incorrect values being entered, resulting in an erroneous electric field strength of 2.86E4 N/C. After correcting the input errors, the participant successfully recalculated the electric field. The conversation highlights the importance of careful data entry in physics calculations.
shimizua
Messages
99
Reaction score
0

Homework Statement


A cat rubs her back on the carpet, and acquires a net charge of -54.1 uC. What is the magnitude of the electric field at a distance 4.01 m from the cat?
and
What would the magnitude of the electric field in the previous problem be,
if the distance from the cat were now tripled?


Homework Equations


F=kq/r^2


The Attempt at a Solution


F=8.9E9(54.1E-6)/4.01^2
my answer came to 2.86E4 N/C which is wrong.

obviously i should be able to get the second part once i understand what i am doing wrong in the first part
 
Physics news on Phys.org
You have calculated the force due to the electric field, not the field itself.

I believe the eq you are looking for is:
<br /> E=\frac{Q}{4\pi\epsilon_0r^{2}}<br />
 
shimizua said:
F=8.9E9(54.1E-6)/4.01^2
my answer came to 2.86E4 N/C

it shouldn't :redface: … did you enter 8.5 instead of 8.9?

(and isn't it 8.988, or just 9.0, anyway?)
 
k so i did

E=54.1E-6/4*3.14*8.85E-12*4.01^2 and got 2.7E4 N/C which still was wrong. what else did i do wrong?
 
Never mind I got it. i was using the right equation, lol i guess i did just enter a number in wrong. funny cause i did it like 10 times. thanks though tiny-tim
 
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
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}...
Back
Top