Normal force Knowledge-Based Practice

Questions

1. 1.

   A block rests on an adjustable inclined plane. As the angle of inclination of the plane relative to the horizontal is gradually increased from $0^\circ$ to $60^\circ$ without the block losing contact, how does the magnitude of the normal force exerted by the plane on the block change?

   • A) It remains constant because the block's weight does not change.
   • B) It decreases because the component of gravity perpendicular to the surface decreases.
   • C) It increases because the incline exerts an increasing upward reaction force.
   • D) It remains constant until the block begins to slip, after which it drops to zero.
2. 2.

   Which force constitutes the Newton's third law reaction pair to the normal force exerted by a horizontal floor on a stationary crate?

   • A) The downward gravitational force exerted by Earth on the crate
   • B) The upward gravitational force exerted by the crate on Earth
   • C) The downward contact force exerted by the crate on the floor
   • D) The horizontal frictional force exerted by the floor on the crate
3. 3.

   A 3.0 kg block and a 2.0 kg block rest in contact with each other on a frictionless horizontal surface. If a constant horizontal force of 15 N pushes the 3.0 kg block directly toward the 2.0 kg block, what is the magnitude of the normal force exerted by the 3.0 kg block on the 2.0 kg block?

   • A) 15 N
   • B) 9.0 N
   • C) 6.0 N
   • D) 3.0 N
4. 4.

   A 2.0 kg block rests on top of a 6.0 kg block, which sits at rest on a level horizontal table. Taking the magnitude of the acceleration due to gravity to be 10 m/s², what is the magnitude of the normal force exerted by the table on the 6.0 kg block?

   • A) 80 N
   • B) 60 N
   • C) 40 N
   • D) 20 N
5. 5.

   A 6.0 kg block rests on a level horizontal floor and is attached to a vertical cable pulling upward with a tension of 25 N. Taking the acceleration due to gravity to be 10 m/s², what is the magnitude of the normal force exerted by the floor on the block?

   • A) 25 N
   • B) 60 N
   • C) 35 N
   • D) 85 N
6. 6.

   A 2.0 kg book is held stationary against a flat vertical wall by a horizontal force of 35 N applied perpendicular to the wall. Taking the magnitude of the acceleration due to gravity to be 10 m/s², what is the magnitude of the normal force exerted by the wall on the book?

   • A) 15 N
   • B) 20 N
   • C) 35 N
   • D) 55 N
7. 7.

   A 3.0 kg block is held stationary against a flat horizontal ceiling by an upward vertical force of 50 N. Taking the magnitude of the acceleration due to gravity to be 10 m/s², what is the magnitude of the normal force exerted by the ceiling on the block?

   • A) 20 N
   • B) 30 N
   • C) 50 N
   • D) 80 N
8. 8.

   A 5.0 kg block rests at equilibrium on a fixed surface inclined at an angle of $37^\circ$ above the horizontal. Taking the magnitude of the acceleration due to gravity to be $10\text{ m/s}^2$, $\sin 37^\circ = 0.60$, and $\cos 37^\circ = 0.80$, what is the magnitude of the normal force exerted by the incline on the block?

   • A) 30 N
   • B) 50 N
   • C) 62.5 N
   • D) 40 N
9. 9.

   A 60 kg person stands on a scale inside an elevator that accelerates upward at 2.0 m/s². Taking the acceleration due to gravity to be 10 m/s², what is the magnitude of the normal force exerted by the scale on the person?

   • A) 480 N
   • B) 720 N
   • C) 600 N
   • D) 120 N
10. 10.

    A 6.0 kg crate rests on a level horizontal floor, and an applied force of 30 N acts on the crate at an angle of 30° above the horizontal. Taking the magnitude of the acceleration due to gravity to be $10\text{ m/s}^2$, what is the magnitude of the normal force exerted by the floor on the crate?

    • A) 30 N
    • B) 45 N
    • C) 60 N
    • D) 75 N

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