Speed of two charged, insulated spheres?

  • Thread starter XianForce
  • Start date
  • #1
16
0

Homework Statement



Two insulating spheres have radii 0.300 cm and 0.500 cm, masses 0.450 kg and 0.700 kg, and uniformly distributed charges of -2.00 µC and 3.00 µC. They are released from rest when their centers are separated by 1.00 m.
(a) How fast will each be moving when they collide? (Hint: Consider conservation of energy and of linear momentum.)

Homework Equations


F = keq1q2/r2
v = at + v0
Δs = v0t + .5at2


The Attempt at a Solution



I found the electrostatic force on the objects. Since they have opposite charges, I know that they move towards each other. I found their accelerations by dividing by their respective masses, and then plugged those into some of the kinematics equations to find the final velocity.

I can see that my methods/assumptions are wrong, I'm just not exactly sure about how to go about this problem.
 

Answers and Replies

  • #2
115
2
Acceleration isn't constant as force increases while spheres get closer
 
  • #3
16
0
Acceleration isn't constant as force increases while spheres get closer
Yes, but then how do I solve it?
 
  • #4
115
2
Your hint says you should use the law of conservation energy and momentum.
 

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