Solve this multiple-choice question and choose the correct option.

Concept Static friction ∝ normal reaction × coefficient of friction. On sand, the surface deforms and shifts, reducing effective normal reaction and reliable contact, so available friction is less. Final AnswerSand yields, reducing normal reaction and friction

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Friction and walking: Sand vs. concrete. Why is it more difficult to walk on a sandy surface than on a rigid concrete road under the same conditions? Choose the correct option.

Difficulty: Easy

Sand yields, reducing normal reaction and friction
Concrete has lower coefficient of friction
Air resistance is higher near sand
Shoes become heavier on concrete

Correct Answer: Sand yields, reducing normal reaction and friction

Explanation:

Concept

Static friction ∝ normal reaction × coefficient of friction.
On sand, the surface deforms and shifts, reducing effective normal reaction and reliable contact, so available friction is less.

Final AnswerSand yields, reducing normal reaction and friction

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