Normal Force Physics Example 3

Follow the full solution, then compare it with the other examples linked below.

Example 3

medium
A 10 kg10 \text{ kg} box on a horizontal floor has a 30 N30 \text{ N} downward push applied to it. What is the normal force? Use g=9.8 m/s2g = 9.8 \text{ m/s}^2.

Solution

  1. 1
    The normal force must balance both the weight and the applied downward force.
  2. 2
    N=mg+Fpush=10×9.8+30=98+30=128 NN = mg + F_{\text{push}} = 10 \times 9.8 + 30 = 98 + 30 = 128 \text{ N}

Answer

N=128 NN = 128 \text{ N}
When an additional downward force is applied to an object on a surface, the normal force increases to maintain equilibrium. The surface pushes back harder to support both the weight and the push.

About Normal Force

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

Learn more about Normal Force →

More Normal Force Examples

Example 1 easy

A [formula] box rests on a horizontal floor. What is the normal force acting on the box? Use [formul

Example 2 medium

A [formula] block rests on a ramp inclined at [formula] to the horizontal. What is the normal force

Example 4 hard

A person ([formula]) stands in an elevator accelerating upward at [formula]. What normal force does

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