Newton's first law (inertia) Knowledge-Based Practice

Questions

1. 1.

   Newton's first law of motion serves as the foundation for classical mechanics. In which type of reference frame does an object maintain a constant velocity when no net external force acts upon it?

   • A) An accelerating frame of reference
   • B) A rotating frame of reference
   • C) A non-inertial frame of reference
   • D) An inertial frame of reference
2. 2.

   A small ball attached to a string is swung in a horizontal circle on a frictionless horizontal table. If the string suddenly breaks, what path does the ball follow across the table immediately after the break?

   • A) A straight line tangent to the circle at the point where the string broke
   • B) A curved path that gradually spirals outward away from the center of the circle
   • C) A straight line directed radially outward away from the center of the circle
   • D) A curved path that continues along the circular arc for a short distance before straightening
3. 3.

   A crate is pushed horizontally across a floor at a constant velocity. According to Newton's first law of motion, how does the magnitude of the horizontal pushing force compare to the magnitude of the opposing friction force?

   • A) The pushing force is greater than the friction force.
   • B) The pushing force is less than the friction force.
   • C) The pushing force is equal to the friction force.
   • D) The friction force must be zero while the crate is moving.
4. 4.

   When a moving vehicle suddenly comes to a stop, an unrestrained passenger continues to move forward. According to Newton's first law of motion, which statement correctly explains this behavior?

   • A) A forward inertial force acts on the passenger to propel them forward.
   • B) The deceleration of the vehicle generates a forward net force on the passenger.
   • C) The momentum of the vehicle is directly transferred to the passenger as an accelerating force.
   • D) The passenger continues in their existing state of forward motion because no horizontal force acts directly on them to stop them.
5. 5.

   An object travels along a circular path at a constant speed. According to Newton's first law of motion, which statement correctly describes the net external force acting on the object?

   • A) A non-zero net external force acts on the object because its direction of motion is changing.
   • B) The net external force acting on the object is zero because its speed remains constant.
   • C) The net external force acting on the object is zero because inertia maintains its curved path.
   • D) A non-zero net external force acts on the object only if its speed increases or decreases.
6. 6.

   According to Newton's first law of motion, how much net force is required to keep an object moving at a constant velocity in frictionless space?

   • A) A constant forward force proportional to the object's speed
   • B) Zero net force
   • C) A net force equal in magnitude to the object's weight
   • D) A continuously applied force equal to the initial force that set it in motion
7. 7.

   A book sliding across a flat floor gradually slows down and comes to a stop. According to Newton's first law of motion, which statement explains why the book stops?

   • A) An unbalanced external force acts on the book to change its motion.
   • B) The force that originally set the book into motion is gradually consumed.
   • C) The book naturally loses its inertia as it travels across the surface.
   • D) Moving objects require a continuous applied force to remain in motion.
8. 8.

   Which physical quantity serves as the direct quantitative measure of an object's inertia?

   • A) Weight
   • B) Velocity
   • C) Mass
   • D) Net force
9. 9.

   In physics, inertia is best defined as the tendency of an object to:

   • A) accelerate proportionally to the net force applied to it.
   • B) resist any change in its existing state of motion.
   • C) exert an equal and opposite force on an interacting body.
   • D) gradually come to rest in the absence of an applied force.
10. 10.

    According to Newton's first law of motion, what happens to an object when the net external force acting on it is equal to zero?

    • A) It remains at rest or continues moving in a straight line at a constant speed.
    • B) It gradually decelerates to rest because a continuous force is required to sustain motion.
    • C) It accelerates uniformly in the direction of its previous displacement.
    • D) It maintains its speed while its direction continuously curves toward its center of mass.

Answers and step-by-step solutions appear after you finish the test.