Calculating Kinetic Energy of Particle B Using Electrical Potential

[srhly]

Particles A (of mass m and charge Q) and B (of mass m and charge 5 Q) are released from rest with the distance between them equal to 0.4939 m. If Q= 31 uC, what is the kinetic energy of particle B at the instant when the particles are 2.4939 m apart? Answer in units of J.

I know that the initial kinetic energy is zero since the particles start from rest. I also know that you can relate the change in electrical potential to kinetic energy. I'm a little confused on how to set it up though.

 

[Tide]

I think the piece of information you're missing is that momentum is conserved in the process.

 

[quicknote]

To calculate the kinetic energy of particle B at the given instant, we can use the formula for electrical potential energy, which is given by U = kQq/r, where k is the Coulomb's constant, Q and q are the charges of the two particles, and r is the distance between them.

In this case, we can plug in the values given in the problem to find the electrical potential energy at the instant when the particles are 2.4939 m apart. This will give us the maximum potential energy that particle B can have at that instant.

Next, we can use the conservation of energy principle to relate this potential energy to the kinetic energy of particle B. Since the initial kinetic energy is zero, the total energy at the given instant will be equal to the potential energy.

Therefore, we can use the formula for kinetic energy, which is given by KE = 1/2mv^2, where m is the mass of the particle and v is its velocity. We can rearrange this equation to solve for v, which will give us the velocity of particle B at the given instant.

Once we have the velocity, we can plug it back into the formula for kinetic energy to calculate the final answer. The final answer will be in units of Joules (J), which is the standard unit for energy.

In summary, to calculate the kinetic energy of particle B at the given instant, we need to first calculate the electrical potential energy at that instant, then use the conservation of energy principle to relate it to the kinetic energy, and finally use the formula for kinetic energy to calculate the final answer.