Normal Force Examples in Physics

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Normal Force.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Physics.

Concept Recap

The perpendicular contact force that a surface exerts on an object pressing against it, directed away from the surface.

The floor pushing up on you so you don't fall through — it acts at a right angle to whatever surface the object touches.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Normal means perpendicular—the force is at right angles to the surface.

Common stuck point: Normal force isn't always equal to weight—it depends on the situation (ramps, elevators).

Worked Examples

Example 1

easy
A 8 \text{ kg} box rests on a horizontal floor. What is the normal force acting on the box? Use g = 9.8 \text{ m/s}^2.

Solution

  1. 1
    The box is in equilibrium on a horizontal surface, so the net vertical force is zero.
  2. 2
    The normal force must balance the weight: N = mg = 8 \times 9.8 = 78.4 \text{ N}
  3. 3
    The normal force acts perpendicular (normal) to the surface, directed upward.

Answer

N = 78.4 \text{ N upward}
The normal force is the contact force exerted by a surface perpendicular to that surface. On a flat horizontal surface with no other vertical forces, the normal force equals the object's weight.

Example 2

medium
A 5 \text{ kg} block rests on a ramp inclined at 30° to the horizontal. What is the normal force on the block? Use g = 9.8 \text{ m/s}^2.

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

medium
A 10 \text{ kg} box on a horizontal floor has a 30 \text{ N} downward push applied to it. What is the normal force? Use g = 9.8 \text{ m/s}^2.

Example 2

hard
A person (60 \text{ kg}) stands in an elevator accelerating upward at 2 \text{ m/s}^2. What normal force does the floor exert on the person? Use g = 9.8 \text{ m/s}^2.
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Background Knowledge

These ideas may be useful before you work through the harder examples.

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