Which of These Four Questions Arising from Modern Ideas of Force

question 182

Multiple Choice

Which of these four questions arising from modern ideas of force and matter is one of the great unanswered questions of contemporary science?

• A) Why do planets move in elliptical orbits?
• B) Why are the inertial mass (defined in Newton's second law) and the mass used in his law of gravitation identical?
• C) What is force?
• D) Why is Mercury's orbit measurably different from that predicted by Newton's laws?

---

Definitions:

Bromecresol Purple

A chemical pH indicator that changes color at a pH range of 5.2 to 6.8, used in various laboratory and medical tests.

Adhesion

The tendency of dissimilar particles or surfaces to cling to one another, often causing materials to stick together.

Hydrogen Bonds

Weak bonds between partially positive hydrogen atoms and partially negative elements like oxygen or nitrogen, crucial in biological structures.

pH Scale

A measure of the acidity or basicity of an aqueous solution, ranging from 0 (most acidic) to 14 (most basic) with 7 as neutral.