Question

(a) apply newton’s first law to each of the following situations. in which situations can you conclude that the object is undergoing a net interaction with one or more other objects? (select all that apply.) a car travels at constant speed around a circular race track. a hydrogen atom remains at rest in outer space. a book slides across the table and comes to a stop. a proton in a particle accelerator moves faster and faster. a spacecraft travels at a constant speed toward a distant star.

Explanation:

Newton's first law (law of inertia) states that an object at rest stays at rest, and an object in motion stays in motion with constant velocity (same speed and direction) unless acted upon by a net external force. A net force causes a change in velocity (speed or direction or both).

• A car travels at constant speed around a circular race track: The direction of the car is changing (since it's moving in a circle), so its velocity is changing. A change in velocity means there is a net force acting on it (centripetal force), so this object is undergoing a net interaction.
• A book slides across the table and comes to a stop: The book's speed is decreasing (it comes to a stop), so its velocity is changing. This is due to the net force of friction acting on it, so there is a net interaction.
• A proton in a particle accelerator moves faster and faster: The proton's speed is increasing, so its velocity is changing. This means a net force (from the accelerator's electric/magnetic fields) is acting on it, so there is a net interaction.
• A hydrogen atom remains at rest in outer space: The atom is at rest and not changing its velocity, so no net force is acting on it (assuming no external forces). So no net interaction.
• A spacecraft travels at a constant speed toward a distant star: The spacecraft's speed and direction are constant (assuming no external forces), so its velocity is constant. Thus, no net force is acting on it, so no net interaction.

Answer:

A. A car travels at constant speed around a circular race track, A. A book slides across the table and comes to a stop, A. A proton in a particle accelerator moves faster and faster