Skip to ContentGo to accessibility pageKeyboard shortcuts menu
OpenStax Logo
Physics

Critical Thinking Items

PhysicsCritical Thinking Items
Search for key terms or text.

Critical Thinking Items

4.1 Force

12.

Only two forces are acting on an object: force A to the left and force B to the right. If force B is greater than force A, in which direction will the object move, given that the object starts from rest?

  1. To the right
  2. To the left
  3. Upward
  4. The object does not move
13.

In a free-body diagram, the arrows representing tension and weight have the same length but point away from one another. What does this indicate?

  1. They are equal in magnitude and act in the same direction.
  2. They are equal in magnitude and act in opposite directions.
  3. They are unequal in magnitude and act in the same direction.
  4. They are unequal in magnitude and act in opposite directions.
14.

An object is at rest. Two forces, X and Y, are acting on it. Force X has a magnitude of x and acts in the downward direction. What is the magnitude and direction of Y, given that the object remains at rest?

  1. The magnitude is x and points in the upward direction.
  2. The magnitude is 2x and points in the upward direction.
  3. The magnitude is x and points in the downward direction.
  4. The magnitude is 2x and points in the downward direction.
15.

Three forces, A, B, and C, are acting on the same object with magnitudes a, b, and c, respectively. Force A acts to the right, force B acts to the left, and force C acts downward. What is a necessary condition for the object to move straight down?

  1. The magnitude of force A must be greater than the magnitude of force B, so a > b.
  2. The magnitude of force A must be equal to the magnitude of force B, so a = b.
  3. The magnitude of force A must be greater than the magnitude of force C, so A > C.
  4. The magnitude of force C must be greater than the magnitude of forces A or B, so A < C > B.

4.2 Newton's First Law of Motion: Inertia

16.

Two people push a cart on a horizontal surface by applying forces F1 and F2 in the same direction. Is the magnitude of the net force acting on the cart, Fnet, equal to, greater than, or less than F1 + F2? Why?

  1. Fnet < F1 + F2 because the net force will not include the frictional force.
  2. Fnet = F1 + F2 because the net force will not include the frictional force
  3. Fnet < F1 + F2 because the net force will include the component of frictional force
  4. Fnet = F1 + F2 because the net force will include the frictional force
17.

True or False: A book placed on a balance scale is balanced by a standard 1-kg iron weight placed on the opposite side of the balance. If these objects are taken to the moon and a similar exercise is performed, the balance is still level because gravity is uniform on the moon’s surface as it is on Earth’s surface.

  1. True
  2. False

4.3 Newton's Second Law of Motion

18.

From the equation for Newton’s second law, we see that Fnet is directly proportional to a and that the constant of proportionality is m. What does this mean in a practical sense?

  1. An increase in applied force will cause an increase in acceleration if the mass is constant.
  2. An increase in applied force will cause a decrease in acceleration if the mass is constant.
  3. An increase in applied force will cause an increase in acceleration, even if the mass varies.
  4. An increase in applied force will cause an increase in acceleration and mass.

4.4 Newton's Third Law of Motion

19.

True or False: A person accelerates while walking on the ground by exerting force F1. The ground in turn exerts force F2 on the person. F1 and F2 are equal in magnitude but act in opposite directions. The person is able to accelerate because the two forces act on the different systems and the net force acting on the person is nonzero.

  1. True
  2. False
20.

A helicopter pushes air down, which, in turn, pushes the helicopter up. Which force affects the helicopter’s motion? Why?

  1. Air pushing upward affects the helicopter’s motion because it is an internal force that acts on the helicopter.
  2. Air pushing upward affects the helicopter’s motion because it is an external force that acts on the helicopter.
  3. The downward force applied by the blades of the helicopter affects its motion because it is an internal force that acts on the helicopter.
  4. The downward force applied by the blades of the helicopter affects its motion because it is an external force that acts on the helicopter.
PreviousNext
Order a print copy
Citation/Attribution

This book may not be used in the training of large language models or otherwise be ingested into large language models or generative AI offerings without OpenStax's permission.

Want to cite, share, or modify this book? This book uses the Creative Commons Attribution License and you must attribute Texas Education Agency (TEA). The original material is available at: https://www.texasgateway.org/book/tea-physics . Changes were made to the original material, including updates to art, structure, and other content updates.

Attribution information
  • If you are redistributing all or part of this book in a print format, then you must include on every physical page the following attribution:
    Access for free at https://openstax.org/books/physics/pages/1-introduction
  • If you are redistributing all or part of this book in a digital format, then you must include on every digital page view the following attribution:
    Access for free at https://openstax.org/books/physics/pages/1-introduction
Citation information

© Feb 19, 2025 Texas Education Agency (TEA). The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University.