Help!! Physics problem/question!

[LauraFairlie]

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Hi guys! I REALLY need help with this problem!

Imagine that we take electrons in pairs, one from the eartg and one from a 60kg person on earth, and send them far away from the earth.

a. How many electron pairs would we have to remove before the electrostatic repulsion between the earth and the person would exceed their gravitational attraction? Give two significant figures in the answer. Assume only for this problem that thte resulting charge separation is the radius of the earth.

b. Roughly, what fraction of the person's electron is this? (Avogadro's number of either protons or neutrons has a mass of nearly 1.0g) For rough approximation, assume that a human is composed of an equal number of neutrons and protons. Answer in one significant figure.

Can you guys give me a step by step symbolic equations to get to the answer? Thank you~!!!

 

[BerkReviewTeach]

Hi guys! I REALLY need help with this problem!

Imagine that we take electrons in pairs, one from the eartg and one from a 60kg person on earth, and send them far away from the earth.

a. How many electron pairs would we have to remove before the electrostatic repulsion between the earth and the person would exceed their gravitational attraction? Give two significant figures in the answer. Assume only for this problem that thte resulting charge separation is the radius of the earth.

b. Roughly, what fraction of the person's electron is this? (Avogadro's number of either protons or neutrons has a mass of nearly 1.0g) For rough approximation, assume that a human is composed of an equal number of neutrons and protons. Answer in one significant figure.

Can you guys give me a step by step symbolic equations to get to the answer? Thank you~!!!

What are the four answer choices for each question and what MCAT practice material do these come from? You wouldn't by chance be hoping to get some homework questions answered would you?

For the first question set Coulomb's Law = Graviational force. You'll see that the radii cancel, so the question is asking you to compare the gravitational force constant (G) to the constant in Coulomb's Law.

For the second question you are given a general assumption that says there are equal numbers of neutrons, protons, and electrons in the body. If you take the charge answer from (a) and divide by Faradays constant that will tell you the moles of electrons that were lost. The total moles of electrons on the human body is its weight in grams divided by 2 (for the number of protons and neutrons, ignoring the electrons because they are essentially massless). You now have the two numbers you need to determine the percentage.

Good luck!