How Many Electrons Are Needed to Accelerate Two Spheres at 25.0g?

AI Thread Summary
To accelerate two 8.55-g spheres at 25.0g, the required force must be calculated using F = ma, resulting in 245 N. The equation F = (kq1q2)/r^2 is then applied to find the charge needed on each sphere, with r being 0.15 m. The calculations yield a charge of approximately 2.47x10^-5 C per sphere. Dividing this charge by the elementary charge (1.6x10^-19 C) results in about 1.55x10^14 electrons per sphere. The initial approach incorrectly used acceleration instead of force, highlighting the importance of proper unit application in physics problems.
joseph5640
Messages
1
Reaction score
0

Homework Statement



Two very small 8.55-g spheres, 15.0 cm apart from centre to centre, are charged by adding equal numbers of electrons to each of them. Disregarding all other forces, how many electrons would you have to add to each sphere so that the two spheres will accelerate at 25.0g when released?

Homework Equations



F= abs( (kq1q2)/r^2)

The Attempt at a Solution



25(9.81)=245

(245)(0.15)^2 = (9.00x10^9)(x^2)
(5.51 / 9.00x10^9) = x^2
2.47x10^-5 C = x = charge of one sphere

(2.47x10^-5) / (1.6x10^-19) = 1.55x10^14 electrons in one sphere

The answer's wrong :(
 
Last edited:
Physics news on Phys.org
You've used acceleration ("245") where you need force. What force is required to produce the acceleration 245 m/s2?
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

How Many Electrons Are Needed to Accelerate Two Charged Spheres at 25g?
Replies
3
Views
3K
Calculating how many surplus electrons on each sphere
Replies
1
Views
6K
Find the electric field on the surface of a sphere using Coulomb's law
Replies
6
Views
2K
Optimal Placement for Net Zero Electrical Force in a System of Charged Spheres
Replies
5
Views
2K
Coulombs's law problem, asked to find an unknown charge.
Replies
8
Views
2K
Force of Gravity & Coulomb's Law Force Question
Replies
3
Views
2K
How Many Electrons Are Missing from the Suspended Plastic Sphere?
Replies
3
Views
8K
Application of Gauss' law - point charge in hollow sphere
Replies
9
Views
4K
How to distribute the charge between two spheres to minimize the potential?
Replies
24
Views
4K
What is the electric field and potential difference between two charged spheres?
Replies
3
Views
2K

Hot Threads

Recent Insights

Back
Top