Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

1. two neutral spheres are suspended from light strings and brought near each no

ID: 2286490 • Letter: 1

Question

1. two neutral spheres are suspended from light strings and brought near each nother. No deflection is observed. Why doesn't the gravitational attraction of the objects cause a noticeable deflection?

a. the objects contain like amounts of positive and negative masses

b. there is no gravitational attraction. Gravitational forces only exist between things like planets and starts

c. the electric forces cancel the gravitational forces

d. the gravitational force between the spheres is too weak to be served compared to the gravitational force between each shpere and the earth

e. an object must be charged for there to be a gravitational force

2. two point charges each experience an acceleration with a magnitude of a due to the electric force between them when they are separeted by a distance equal to r. What accelerations do they experience when they are separated by a distance of r/2?

a. a/4 b. a/2 c. 2a d. 4a e. a

Explanation / Answer

(1)

Because the gravitational force between the spheres is too weak to be served compared to the gravitational force between each shpere and the earth

Thus, the correct option is (d)

--------------------------------------------------------------------------------------------------------------------------------

(2)

Equation for electrostatic force between charge q1 and q2 separated by a distance r :

      F = q1 q2 /r^2

From Newton's law F = ma, therefore

ma = q1 q2 /r^2

Acceleration varies inversely with square of the distance between the charges.

Here, distance is r /2 , so acceleration varies with 1/ ( r /2 )^2

Thus, the correct option is (d)