Question

a spaceship moving through deep space will continue moving at the same speed forever. what is the name of the property that allows this to happen?

a. mass
b. inertia
c. normal force
d. force

Explanation:

• Mass: It is a measure of the amount of matter in an object. While mass is related to inertia (as \(F = ma\) and \(a=\frac{F}{m}\), mass affects how an object responds to a force), it is not the property that directly causes an object to continue moving at a constant speed.
• Inertia: Inertia is the property of an object to resist changes in its state of motion. According to Newton's first law of motion (the law of inertia), an object in motion will stay in motion with a constant velocity (in a straight line and at a constant speed) unless acted upon by an external force. In deep - space, if there is no external force (neglecting gravitational forces from very distant objects in a simplistic view), the spaceship's inertia keeps it moving at the same speed.
• Normal force: The normal force is a contact force that acts perpendicular to the surface of contact. For example, when a book is on a table, the table exerts a normal force on the book. It has no relation to an object moving in deep - space with no external forces in the context of continuing its motion.
• Force: A force is an interaction that can change the motion of an object (\(F = ma\)). If there were a net force on the spaceship, its speed (or direction) would change. But the question is about the property that allows it to move at a constant speed without a force changing its state, so force is not the answer.

Answer:

B. Inertia