How Do You Calculate the Electric Charge on a Suspended Cork Ball?

In summary, the problem involves a suspended cork ball with a mass of 1.5x10^-4 kg and a suspension thread with a length of .1m. When equal electric charges are placed on the two balls, the repulsive force causes the suspended ball to make a 45 degree angle with the vertical. The magnitude of the electric charge can be found by using the equations f= k (q x q)/ r^2 and T=IA and considering all the forces acting on the suspended cork ball. However, in the attempt at a solution, the calculation of R and the use of torque did not yield the correct answer. Further consideration of the x and y components of the weight force and coulomb force may be
  • #1
astroman707
61
5

Homework Statement


A cork ball is suspended at an angle from the vertical of a fixed cork ball below. The mass of the suspended ball is 1.5x10^-4 kg. The length of the suspension thread is .1m. The fixed ball is located .1m directly below the point of suspension of the suspended ball. Assume that when equal electric charges are placed on the two balls, the electric repulsive force pushes the suspended ball up so it's thread makes an angle of 45 degrees with the vertical. What is the magnitude of the electric charge?

Homework Equations


f= k (q x q)/ r^2
T=IA

The Attempt at a Solution


I drew a line from the fixed ball to the suspended ball, and using the (.1)sin(45degrees), I got R= .071.
I then calculated the weight force of the suspended ball, which is .00147N.
I thought I could used a torque formula to solve for the force, but it wasn't working. So I tried breaking up the weight force and the coulomb force into vector components and making those components equal to each other and solving for q, but the x and y components had different values for q, which doesn't make sense.
 
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  • #2
astroman707 said:
the x and y components had different values for q
how so ? Can you post a drawing of what you did ?
 
  • #3
astroman707 said:

Homework Statement


A cork ball is suspended at an angle from the vertical of a fixed cork ball below. The mass of the suspended ball is 1.5x10^-4 kg. The length of the suspension thread is .1m. The fixed ball is located .1m directly below the point of suspension of the suspended ball. Assume that when equal electric charges are placed on the two balls, the electric repulsive force pushes the suspended ball up so it's thread makes an angle of 45 degrees with the vertical. What is the magnitude of the electric charge?

Homework Equations


f= k (q x q)/ r^2
T=IA

The Attempt at a Solution


I drew a line from the fixed ball to the suspended ball, and using the (.1)sin(45degrees), I got R= .071.
I then calculated the weight force of the suspended ball, which is .00147N.
What is R?How is it related to the problem?
astroman707 said:
I thought I could used a torque formula to solve for the force, but it wasn't working. So I tried breaking up the weight force and the coulomb force into vector components and making those components equal to each other and solving for q, but the x and y components had different values for q, which doesn't make sense.
what are the directions of the coordinate axes x and y?
How many forces act on the suspended cork? It looks that you forgot the tension force.
 

1. What is a charged pendulum problem?

A charged pendulum problem is a physics problem that involves a pendulum with an electric charge. The pendulum is typically made up of a conducting material and is suspended in a uniform electric field. The goal of the problem is to determine the motion of the pendulum and its equilibrium position.

2. What are the key equations used in solving a charged pendulum problem?

The key equations used in solving a charged pendulum problem are the equations of motion for a pendulum, which include the gravitational force, the electric force, and the restoring force. These equations can be set equal to each other to find the equilibrium position of the pendulum and to determine its motion.

3. How does the charge of the pendulum affect its motion?

The charge of the pendulum affects its motion by introducing an electric force into the equation of motion. This force can either add to or oppose the gravitational force, depending on the direction of the electric field. This can result in a change in the equilibrium position and the amplitude of the pendulum's motion.

4. Can a charged pendulum problem be solved analytically?

Yes, a charged pendulum problem can be solved analytically by using the equations of motion and solving for the equilibrium position and the motion of the pendulum. However, for more complex problems, numerical methods may be necessary.

5. What are some real-world applications of charged pendulum problems?

Charged pendulum problems have applications in various fields, including physics, engineering, and astronomy. For example, they can be used to study the motion of charged particles in electric and magnetic fields, to design and calibrate instruments such as mass spectrometers, and to analyze the behavior of celestial bodies in the presence of electromagnetic forces.

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