Question

3. [3 pts] To put this (problem 2) into perspective, calculate the mass of an object that would have a gravitational force of equivalent magnitude. 4. 12 pts] You walk in to the physics lab and observe that the electroscope is charged. What would happen if you brought a negatively charged object to the electroscope? Explain your answer. a. Leaves spread further b. Leaves move closer c. Stays the same d. Not enough information

Answer 1

3) Suppose the magnitude is . So, the mass will be:

$\frac{GMm}{r^2}=K$ (From Newton's law)

$mg=K$

$m=\frac{K}{g}$

4) Suppose the electroscope is postively charged as you entered the lab. When the negatively charged rod is brought towards the electroscope, the positive charges from the scope are attracted towards the rod. So, the leaves will lose charges which in turn cause the leaves to move closer.

Now if the electroscope was negatively charged before, bringing the neagtive charged rod, will repell the electrons into the leaves causing it to move apart much further.

So, the answer is D.