Free Body Diagram Quiz with Answers: AP Physics C Mechanics

📚 Quick Study Guide

• 📏 Newton's First Law: An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by a force.
• 🍎 Newton's Second Law: The net force on an object is equal to the mass of the object times its acceleration: $F_{net} = ma$.
• 🚀 Newton's Third Law: For every action, there is an equal and opposite reaction.
• ✍️ Free Body Diagram (FBD): A visual representation of all forces acting on an object. Key forces to consider:
  • Weight ($W = mg$)
  • Normal Force ($N$)
  • Tension ($T$)
  • Friction ($f$)
  • Applied Force ($F_{applied}$)
• 🧮 Steps to Draw an FBD:
  1. Identify the object of interest.
  2. Draw a dot to represent the object.
  3. Draw vectors representing each force acting on the object, with the tail of the vector at the dot.
  4. Label each force vector clearly.
• ⚙️ Friction:
  • Static Friction: $f_s \le \mu_s N$
  • Kinetic Friction: $f_k = \mu_k N$

🧪 Practice Quiz

1. Question 1: A block of mass $m$ rests on a horizontal surface. A horizontal force $F$ is applied to the block. Which of the following free-body diagrams best represents the forces acting on the block?
   1. 
   2. 
   3. 
   4. 
2. Question 2: A ball is thrown upwards. At the highest point of its trajectory, which forces act on the ball?
   1. Only the upward force.
   2. Only the downward force due to gravity.
   3. Both upward and downward forces.
   4. No forces act on the ball.
3. Question 3: A crate is sliding down an inclined plane at a constant speed. Which of the following statements is true about the forces acting on the crate?
   1. The net force on the crate is zero.
   2. The net force on the crate is directed down the incline.
   3. The net force on the crate is directed up the incline.
   4. The normal force is equal to the weight of the crate.
4. Question 4: A lamp is suspended from the ceiling by a rope. Which of the following forces should be included in the free-body diagram of the lamp?
   1. Tension in the rope acting upwards.
   2. Weight of the lamp acting downwards.
   3. Both tension and weight.
   4. Neither tension nor weight.
5. Question 5: A book is at rest on a table. What forces are acting on the book?
   1. Only the weight of the book.
   2. Only the normal force from the table.
   3. Both the weight and the normal force.
   4. No forces are acting on the book.
6. Question 6: A car is moving at a constant velocity on a straight, level road. What is the net force acting on the car?
   1. Equal to the force applied by the engine.
   2. Equal to the friction force.
   3. Zero.
   4. Impossible to determine without knowing the car's mass.
7. Question 7: A box is pushed across a rough horizontal floor. The forces acting on the box include a pushing force, friction, weight, and normal force. If the pushing force is constant and the box is accelerating, which statement is correct?
   1. The pushing force is equal to the friction force.
   2. The pushing force is greater than the friction force.
   3. The pushing force is less than the friction force.
   4. The normal force is equal to the friction force.