Question

Why do we use a spaceship in outer space, far from other objects, to illustrate the principle that an object that does not interact with anything travels at constant speed in a straight line (Newton's first law)? Why not a car or a train? (Select all that apply.)

Answer 1

A spaceship is used to illustrate Newton's first law because it can travel at a constant speed in a straight line in the vacuum of space without encountering any external forces like air resistance or friction.

Step-by-step explanation:

The reason we use a spaceship in outer space to illustrate Newton's first law is because a spaceship can travel in a straight line and at a constant speed in the vacuum of space. This is because there is no air resistance or other forces acting upon it. On the other hand, a car or a train would encounter friction from the ground and air resistance, which would ultimately affect their speed and motion.

For example, a train on a track encounters friction between its wheels and the rails, which causes it to slow down. Also, cars encounter air resistance, especially at higher speeds, which can affect their ability to maintain a constant speed.

Therefore, using a spaceship in outer space allows us to isolate the effects of forces like air resistance or friction and understand the concept of an object traveling at a constant speed in a straight line in the absence of external forces.

Answer 2

Complete Question: Why do we use a spaceship in outer space, far from other objects, to illustrate the principle that an object that does not interact with anything travels at constant speed in a straight line (Newton's first law)? Why not a car or a train? (Select all that apply.)

(1) A car or train touches other objects, and interacts with them.

(2) A car or train can't travel fast enough.

(3) The spaceship has negligible interactions with other objects.

(4) A car or train interacts gravitationally with the Earth.

(5) A spaceship can never experience a gravitational force.

Answer:

(1), (3), (4), (5)

Step-by-step explanation:

In order to be able to move in a straight line at constant speed forever, as stated by Newton's first law, the object can't be subject to any external net force that can change its momentum.

1) A car, or train, interacts with other objects (the air, the road surface, or the rails, for instance) which means that sooner or later, it will come to an stop, so, for this reason, is not a good fit for that purpose.

3) As it is assumed that the spaceship has negligible interactions with another objects, it will continue moving in a straight line at a constant speed, forever, so it's a good fit to explain Newton's first law.

4) As the train, or a car, or any earthling object, is subject to the gravitational attractive force from Earth, it is not possible for them to move along a straight line at a constant speed forever, as stated by Newton's first law, so a train or a car definitely aren't a good fit in order to explain it.

5) Even though a spaceship can actually experiment a gravitational force from any mass close enough to it, as stated by Newton's Universal Law of Gravitation, in order to simplify things, in this case, usually we neglect any of them.