please check:

Conductors can be charged by ___, while insulators cannot.
a. grounding
b. induction
c. polarization
d. contact

D

Which of the following is not true for both gravitational and electric forces?
a. the inverse square distance law applies
b. forces are proportional to physical properties
c. potential energy is a function of distance of separation
d. forces are either attractive or repulsive

D

correct.

induction

For the statement "Conductors can be charged by ___, while insulators cannot," the correct answer is D. Contact.

Regarding the statement "Which of the following is not true for both gravitational and electric forces?"

The correct answer is D. Forces are either attractive or repulsive. This statement is incorrect because both gravitational and electric forces can be either attractive or repulsive, depending on the charges involved or masses attracting each other.

To check these answers, we need to understand the concepts discussed in the questions.

Question 1: Conductors and Insulators

Conductors are materials that allow the flow of electric charge, while insulators are materials that do not allow the flow of electric charge. Conductors can become charged through various methods, including grounding, induction, polarization, and contact. In this question, we need to identify the method that can charge conductors but not insulators.

Option D, "contact," is the correct answer. Conductors can be charged through contact with other charged objects, but insulators do not allow the transfer of charge through contact. Therefore, option D is the correct choice.

Question 2: Gravitational and Electric Forces

Gravitational and electric forces are fundamental forces that act between objects. To check the given options, we need to compare the common characteristics of both forces.

a. The inverse square distance law applies: Both gravitational and electric forces follow the inverse square law, where the force between two objects decreases with the square of the distance between them. This statement is true for both forces.

b. Forces are proportional to physical properties: Both gravitational and electric forces are proportional to specific properties. Gravitational forces depend on the mass of the objects, while electric forces depend on the charges of the objects involved. This statement is true for both forces.

c. Potential energy is a function of distance of separation: Both gravitational and electric potential energies are determined by the separation distance between the interacting objects. This statement is true for both forces.

d. Forces are either attractive or repulsive: This statement is not true for both forces. Gravitational forces are always attractive, meaning they pull objects towards each other. On the other hand, electric forces can be attractive (opposite charges) or repulsive (like charges).

Based on this analysis, option D is the correct answer as it does not hold true for both gravitational and electric forces.