5 Ways To Find Normal Force

Imagine a block sitting on a table. The force of gravity pulls the block toward the Earth, but clearly, there is some force at work preventing the block from crashing through the table and finishing its descent toward the ground. The force responsible for stopping the block in spite of gravitational force is the normal force.

In this equation, N refers to the normal force, m refers to the object’s mass, and g refers to the acceleration of gravity. For an object sitting on a flat surface, with no outside forces at work, the normal force is equal to the object’s weight. In order to keep the object still, the normal force must be equal to the force of gravity at work on the object. The force of gravity at work on the object is that object’s weight, or its mass multiplied by the acceleration of gravity. Example: Find the normal force of a block with a mass of 4. 2 kg.

Note that the gravitational acceleration at the Earth’s surface is a constant: g = 9. 8 m/s2 Example: weight = m * g = 4. 2 * 9. 8 = 41. 16

Example: The normal force is 41. 16 N.

For this equation, N refers to the normal force, m refers to the object’s mass, g refers to the acceleration of gravity, and x refers to the angle of incline. Example: Find the normal force of a block with a mass of 4. 2 kg, sitting on a ramp with an incline of 45 degrees.

This value is often determined by a calculator, since the cosine of any angle is constant to that angle, but you can compute it manually, as well. Example: cos (45) = 0. 71

Note that the gravitational acceleration at the Earth’s surface is a constant: g = 9. 8 m/s2 Example: weight = m * g = 4. 2 * 9. 8 = 41. 16

Example: N = m * g * cos(x) = 41. 16 * 0. 71 = 29. 1

Note that for an object sitting on an incline, the normal force should be less than the weight of the object. Example: The normal force is 29. 1 N.

N refers to the normal force, m refers to the object’s mass, g refers to the acceleration of gravity, F refers to the outside force, and x refers to the angle between the object and the direction of the outside force. Example: Find the normal force of a block with a mass of 4. 2 kg, when a person is pressing down on the block at a 30 degree angle with a force of 20. 9 N.

Note that the gravitational acceleration at the Earth’s surface is a constant: g = 9. 8 m/s2 Example: weight = m * g = 4. 2 * 9. 8 = 41. 16

Example: sin(30) = 0. 5

Example: 0. 5 * 20. 9 = 10. 45

Example: 10. 45 + 41. 16 = 51. 61

Example: The normal force is 51. 61 N.

N refers to the normal force, m refers to the object’s mass, g refers to the acceleration of gravity, F refers to the outside force, and x refers to the angle between the object and the direction of the outside force. Example: Find the normal force of a block with a mass of 4. 2 kg, when a person is pulling up at the block at a 50 degree angle with a force of 20. 9 N.

Note that the gravitational acceleration at the Earth’s surface is a constant: g = 9. 8 m/s2 Example: weight = m * g = 4. 2 * 9. 8 = 41. 16

Example: sin(50) = 0. 77

Example: 0. 77 * 20. 9 = 16. 01

Example: 41. 16 – 16. 01 = 25. 15

Example: The normal force is 25. 15 N.

In this equation, f stands for friction, μ refers to the coefficient of friction, and N refers to the normal force of the object. A “coefficient of friction” is the ratio between frictional resistance to normal force, which is responsible for pressing the two opposing surfaces together.

Both sides of the original equation were divided by μ, thereby isolating normal force on one side while accounting for the coefficient of friction and kinetic friction on the opposite side. Example: Find the normal force of a block when the coefficient of friction is 0. 4 and the amount of kinetic friction itself is 40 N.

Example: N = f / μ = 40 / 0. 4 = 100

Example: The normal force is 100. 0 N.