Normal Force Quiz with Answers: Test Your AP Physics Knowledge

📚 Quick Study Guide

• ⚖️ Normal force ($F_N$) is the force exerted by a surface on an object in contact with it. It's always perpendicular to the surface.
• 📐 If an object is on a horizontal surface and no other vertical forces are acting, the normal force is equal to the object's weight: $F_N = mg$, where $m$ is mass and $g$ is the acceleration due to gravity ($9.8 m/s^2$).
• ⬆️ On an inclined plane, the normal force is equal to the component of the gravitational force perpendicular to the plane: $F_N = mg \cos(\theta)$, where $\theta$ is the angle of inclination.
• ✍️ The normal force adjusts to balance other forces. If an external force is applied vertically, the normal force will change accordingly: $F_N = mg + F_{applied}$.
• 🚧 Normal force is a contact force; it only exists when there is physical contact between the object and the surface.

🧪 Practice Quiz

1. A 5 kg block rests on a horizontal surface. What is the normal force acting on the block?
   1. 4.9 N
   2. 9.8 N
   3. 49 N
   4. 98 N
2. A 10 kg box is placed on an inclined plane with an angle of 30 degrees. What is the magnitude of the normal force acting on the box?
   1. 98 N
   2. 84.9 N
   3. 49 N
   4. 0 N
3. A student pushes down on a book resting on a table with a force of 5 N. If the book has a mass of 2 kg, what is the normal force exerted by the table on the book?
   1. 14.6 N
   2. 19.6 N
   3. 24.6 N
   4. 5 N
4. A 3 kg block is resting on a horizontal surface. If a force of 10 N is applied upwards, what is the normal force acting on the block?
   1. 39.4 N
   2. 19.4 N
   3. 30 N
   4. 10 N
5. A 7 kg block slides down a frictionless inclined plane at an angle of 45 degrees. What is the normal force acting on the block?
   1. 48.5 N
   2. 69.3 N
   3. 98 N
   4. 0 N
6. A 1 kg object is placed on a scale in an elevator. If the elevator accelerates upwards at 2 m/s², what is the reading on the scale (i.e., the normal force)?
   1. 7.8 N
   2. 2 N
   3. 9.8 N
   4. 11.8 N
7. A block is at rest on a table. Which of the following statements is true about the normal force?
   1. It is always equal to the weight of the block.
   2. It is always greater than the weight of the block.
   3. It is the force exerted by the block on the table.
   4. It is the force exerted by the table on the block.