Friction - Exercise - Ten New Questions

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After solving so many problems on friction from #HCVerma 's #Conceptsofphysics Part-I, Try to solve these new questions on friction to have a good practice. Answers and hints if any will be given in the coming blog.

EXERCISE on FRICTION  --Ten New Questions 

1.     A bamboo ladder having mass 'm' kg is resting against a smooth wall. The coefficient of friction between the ladder and the floor is µ. What are the Normal forces at each end of the ladder if it is about to slip on the floor. (Assume the weight of ladder acts at the center of the ladder).  
  

2.   A bamboo ladder of mass 20 kg is resting on a floor (having coefficient of friction µ₁ between the surfaces) against a wall (having coefficient of friction µ₂ between the surfaces). The ladder's both ends are in a limiting state of friction. Find, 

(i) Normal forces on the ladder at both ends.
(ii) Total forces at both ends.
(Assume the weight of ladder acts at the center of the ladder).      

        

3.    A person of mass 'm' kg is running on a long flat plywood board placed on a plane horizontal surface at maximum speed without slipping on the board. The coefficient of friction between his feet and the board is µ₁  and between the board and the floor is µ₂. What should be the minimum mass of the board 'M' so that it does not slip on the floor.     

4.     Two blocks connected by a string are placed on two opposite planes as shown in the figure below. What should be the value of the coefficient of static friction µ for both blocks (with respect to the surface) to be at a critical state of static friction.

Diagram for question number -4

 
         

5.     A car moving with a speed of 30 km/hr approaches a downslope of 30° from horizontal. The driver at once sees a big tree fell across the road 50 m ahead and decides to apply hard brakes but till then the speed of the car increases to 60 km/hr on the slope. Will the car stop before hitting the tree. If yes find the distance between the tree and the stopped car. Otherwise, calculate the speed of the car at which it hits the tree. Take the mass of the car 600 kg and the coefficient of friction between the tyres and the road 0.20. 
      

6.  A dome in the shape of a hemisphere having a radius equal to 15 m is constructed over a building. A Mason of weight 60 kg rides to the top of the dome to repair it. How far away from the crown of the dome in terms of angular distance from vertical (taking the center of the hemisphere as origin) can he stand without slipping. The coefficient of static friction between his feet and the surface of the dome is 0.3. 
         

7. Seeing a crowded bus a boy rides to its roof holding window bars but there is nothing to hold there when the bus speeds up. Find the maximum acceleration of the bus on a straight horizontal road so that the boy does not slide on the roof. Mass of the boy is 50 kg and the coefficient of static friction between the body of the boy and the roof surface is 0.4. 
         

8.  Solve the problem no 7 if the bus accelerates on a down sloping road with an angle of inclination 30° from the horizontal. 
        

9.   A person is trying to pull a block of wood having a mass of 20 kg up along a sloping road with the help of a rope that makes an angle of 30° from the road. The road itself is sloping at an angle of 30° from the horizontal. What should be minimum tension in the rope to overcome the resistance and just slide up the block? The coefficient of static friction between the block and the road is 0.25.  
       

10.   In the problem number 9 what should be the minimum coefficient of friction between the road and the feet of the man so that he does not slip on the road. Take the weight of the man=50 kg  
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CHAPTER- 14 - Fluid Mechanics


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CHAPTER- 13 - Fluid Mechanics

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HC Verma's Concepts of Physics, Chapter-8, WORK AND ENERGY

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HC Verma's Concepts of Physics, Chapter-7, Circular Motion

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HC Verma's Concepts of Physics, Chapter-6, Friction

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For more practice on problems on friction solve these "New Questions on Friction" .

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HC Verma's Concepts of Physics, Chapter-5, Newton's Law's of Motion

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HC Verma's Concepts of Physics, Chapter-4, The Forces

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HC Verma's Concepts of Physics, Chapter-3, Kinematics-Rest and Motion:---

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Chapter -2, "Vector related Problems"

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