A block of mass $5,\text{kg}$ is placed on a rough horizontal surface. The coefficient of kinetic friction between the block and the surface is $0.30$. What is the magnitude of the kinetic friction force acting on the block?

Step-by-step solution

1. Step 1: Identify the normal force. Since the block is on a horizontal surface, the normal force equals the weight: $N=mg=5\times 9.8=49,\text{N}$.
2. Step 2: Apply the kinetic friction formula $f_k={\mu }_{k}N=0.30\times 49=14.7,\text{N}$.
3. Step 3: Conclude that the kinetic friction force is $14.7,\text{N}$.

Concept tested: Coefficient of kinetic friction calculation

Published 4 October 2026 · How this solution was prepared and checked