Friction
A wooden block resting on a rough horizontal floor just begins to slide when a horizontal pull equal to 24 N is applied, while the block weighs 60 N. What is the coefficient of static friction between the block and the floor?
Select the correct option:
Solution
0.4
From NCERT Class 11, Chapter 5 (Laws of Motion), the limiting (maximum) static friction is given by f_max = μ_s N, where N is the normal reaction. On a horizontal floor with only weight acting vertically, the normal reaction equals the weight, so N = 60 N. The block is on the verge of sliding when the applied horizontal force equals the limiting static friction, so f_max = 24 N. Rearranging, μ_s = f_max / N = 24 / 60 = 0.4. Option 0.6 incorrectly inverts the ratio as 60/24 scaled, or confuses force with weight. Option 0.25 corresponds to taking 24/96, using a wrong normal force. Option 0.5 corresponds to 30/60 and does not match the given applied force. Plausibility check: coefficients of static friction for wood on a typical floor lie around 0.3 to 0.5, so 0.4 is physically realistic, and being dimensionless it correctly carries no units, confirming the result.
🔒 Solution Hidden from View
Submit your answer to unlock the detailed step-by-step solution.
More friction Practice Questions
A cyclist of total mass 70 kg rides up a slope inclined at 30 degrees to the horizontal at a steady ...
A cyclist of total mass 70 kg rides up a slope inclined at 30 degrees to the horizontal at a steady ...
A wooden crate of mass 10 kg is dragged 5 m up a rough incline by a force, and friction exerts a con...
A wooden crate of mass 10 kg is dragged 5 m up a rough incline by a force, and friction exerts a con...
A block placed on a rough inclined plane remains on the verge of sliding when the incline is tilted ...
A block placed on a rough inclined plane remains on the verge of sliding when the incline is tilted ...
A hockey puck sliding across rough ice with an initial speed of 12 m/s comes to rest after travellin...
A hockey puck sliding across rough ice with an initial speed of 12 m/s comes to rest after travellin...
A 10 kg loaded sled is dragged 25 m across level ground at constant velocity by a horizontal rope, w...
A 10 kg loaded sled is dragged 25 m across level ground at constant velocity by a horizontal rope, w...
About This Question
- Subject
- physics
- Chapter
- laws of motion
- Topic
- friction
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
0.4
From NCERT Class 11, Chapter 5 (Laws of Motion), the limiting (maximum) static friction is given by f_max = μ_s N, where N is the normal reaction. On a horizontal floor with only weight acting vertically, the normal reaction equals the weight, so N = 60 N. The block is on the verge of sliding when the applied horizontal force equals the limiting static friction, so f_max = 24 N. Rearranging, μ_s = f_max / N = 24 / 60 = 0.4. Option 0.6 incorrectly inverts the ratio as 60/24 scaled, or confuses force with weight. Option 0.25 corresponds to taking 24/96, using a wrong normal force. Option 0.5 corresponds to 30/60 and does not match the given applied force. Plausibility check: coefficients of static friction for wood on a typical floor lie around 0.3 to 0.5, so 0.4 is physically realistic, and being dimensionless it correctly carries no units, confirming the result.
This easy difficulty physics question is from the chapter laws of motion, covering the topic of friction. It appeared in the 2025 exam.
Looking for more practice? Explore all physics questions or browse laws of motion questions on RankGuru.