Friction Worksheet

Objective Type Questions
 

1. Fill in the blanks:
   Static friction is ___________ than sliding friction.
   
   
2. Analogy:
   Greater than sliding friction: _______ :: Lesser than sliding friction: Rolling friction
   
   
3. Unscramble the given words based on the clues given:
   
    
4. State whether the statement is true or false:
   Friction can completely be eliminated by making the surface perfectly smooth.
   
   Multiple Choice Questions
    
5. Whenever the surfaces in contact tend to move or move with respect to each other, the force of friction comes into play
   (a) only if the objects are solid
   (b) only if one of the two objects is liquid
   (c) only if one of the two objects is gaseous
   (d) irrespective of whether the objects are solids, liquids or gases.
    
6. To sharpen the blade of a knife by rubbing it against a surface, which of the following will be most suitable?
   (a) Stone
   (b) Plastic block
   (c) Wooden block
   (d) Glass block
    
7. Amit is playing with a toy car. It is released with some initial speed. The car will travel farthest on
   (a) muddy surface
   (b) polished marble surface
   (c) cemented surface
   (d) brick surface
    
8. If we apply oil to door hinges, the friction will
   (a) Increase
   (b) decrease
   (c) disappear altogether
   (d) will remain unchanged
   
   
9. Which of the following statements is incorrect?
   (a) Friction acts on a ball rolling along the ground
   (b) Friction acts on a boat moving on water
   (c) Friction acts on a bicycle moving on a smooth road
   (d) Friction does not act on a ball moving through air
   
   Subjective Questions
   
   
10. What is the force responsible for wearing out bicycle tyres?
     
11. Give one example where ball bearings are used.
     
12. Give three examples of a streamlined body.
     
13. Will the force of friction come into play when a raindrop rolls down a glass windowpane?
     
14. Is friction a foe or friend?
     
15. What do you mean by fluid friction? How can fluid friction be reduced?
     
16. Why do the soles of the shoes have grooves?
     
17. Can static friction also produce heat when two bodies try to slide over one another?
     
    Assertion-Reasoning Questions
    
    Below questions consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below:
     
18. Assertion: Fine powder is sprinkled on the carrom board to increase the friction.
    Reason: Friction is a self-adjusting force.
    
    
19. Assertion: Fluid friction can be reduced by giving suitable shapes to the bodies moving in it.
    Reason: Gases and liquids are called fluids.
    
    Case-Based Questions
    
    
20. In a large commercial center, there are four paths to reach the main road. One of the paths has mud, the second is laid with polished marble, the third is laid with granite and the fourth has a gravel surface. It is raining heavily, and Surbhi wishes to reach the main road.
    (a) The path on which Surbhi is least likely to slip is
    (i) muddy surface
    (ii) polished marble
    (iii) granite
    (iv) gravel surface
    (b) Give a reason for the selection of the choice of option in part (a).
    (c) In which direction does the force of friction act?
    (d) What is friction?

Objective Type Questions
 

1. Fill in the blanks:
   Static friction is ___________ than sliding friction.
   Solution: Static friction is greater than sliding friction.
   
   
2. Analogy:
   Greater than sliding friction: _______ :: Lesser than sliding friction: Rolling friction
   Solution: Greater than sliding friction: Static friction: Lesser than sliding friction: Rolling friction
   
   
3. Unscramble the given words based on the clues given:
   
   Solution:
   (i) LUBRICANTS
   (ii) DRAG
   (iii) AEROPLANE
   (iv) SPRING BALANCE
   
   
4. State whether the statement is true or false:
   Friction can completely be eliminated by making the surface perfectly smooth.
   Solution: False. Friction can never be eliminated because no surface is perfectly smooth. Some irregularities will always be present on the surface.
   
   Multiple Choice Questions
    
5. Whenever the surfaces in contact tend to move or move with respect to each other, the force of friction comes into play
   (a) only if the objects are solid
   (b) only if one of the two objects is liquid
   (c) only if one of the two objects is gaseous
   (d) irrespective of whether the objects are solids, liquids or gases.
   Correct option: (d) irrespective of whether the objects are solids, liquids or gases.
   Solution: Whenever the surfaces in contact tend to move or move over each other, the force of friction comes into play, irrespective of whether the objects are solids, liquids or gases. 
    
6. To sharpen the blade of a knife by rubbing it against a surface, which of the following will be most suitable?
   (a) Stone
   (b) Plastic block
   (c) Wooden block
   (d) Glass block
   Correct option: (a) Stone
   Solution: Rubbing a stone against the blade of a knife can sharpen it.
    
7. Amit is playing with a toy car. It is released with some initial speed. The car will travel farthest on
   (a) muddy surface
   (b) polished marble surface
   (c) cemented surface
   (d) brick surface
   Correct option: (b) polished marble surface
   Solution:  Polished marble surface will provide less friction than any other surface. Thus, the toy car will travel farthest on the polished marble surface.
    
8. If we apply oil to door hinges, the friction will
   (a) Increase
   (b) decrease
   (c) disappear altogether
   (d) will remain unchanged
   Correct option: (b) decrease
   Solution:  Oiling of the hinges of the door decreases friction.
   
   
9. Which of the following statements is incorrect?
   (a) Friction acts on a ball rolling along the ground
   (b) Friction acts on a boat moving on water
   (c) Friction acts on a bicycle moving on a smooth road
   (d) Friction does not act on a ball moving through air
   Correct option: (d) Friction does not act on a ball moving through air
   Solution: The pressure exerted by the air around us is known as atmospheric pressure.
   
   Subjective Questions
   
   
10. What is the force responsible for wearing out bicycle tyres?
    Solution: Frictional force
     
11. Give one example where ball bearings are used.
    Solution: Ceiling fan
     
12. Give three examples of a streamlined body.
    Solution: Aeroplanes, birds, ships.
     
13. Will the force of friction come into play when a raindrop rolls down a glass windowpane?
    Solution: Yes, friction comes into play when two surfaces are in contact, e.g. glass and water.
     
14. Is friction a foe or friend?
    Solution: Friction is a necessary evil. There are instances in daily life where friction is a necessity.
    Friction as a friend:
    Friction plays a vital role in our daily life.
    (i) Construction of buildings is possible only because of friction.
    (ii) We can write because of friction between the paper and the pen's tip.
    (iii) Without friction between our shoes and the ground, we cannot walk.
    (iv) A horse cannot pull a cart unless friction furnishes him with a secure foothold.
    Friction as a foe:
    (i) The main disadvantage of friction is that it produces heat in the moving parts of machines, which causes wear and tear of the parts.
    (ii) It opposes the motion.
    (iii) A lot of energy is wasted in overcoming friction.
    (iv) It causes wear and tear of the soles of shoes.
    (v) Friction produces unpleasant noise in the machines.
     
15. What do you mean by fluid friction? How can fluid friction be reduced?
    Solution: Fluid friction:
    (i) Liquids and gases are together known as fluids.
    (ii) Substances which can flow easily are called fluids.
    (iii) The frictional force exerted by fluids is known as drag or fluid friction.
    (iv) The frictional force on an object moving through a fluid depends on its speed with respect to the fluid.
    (v) When objects move through a fluid, the friction
    o Reduces the speed of the object
    o Leads to losing some of the energy possessed by the object in overcoming it
    Fluid friction is reduced by designing streamlined shapes:
    o An aeroplane has a streamlined shape to reduce air drag.
    o Speed boats are provided with streamlined shapes to reduce water drag.
     
16. Why do the soles of the shoes have grooves?
    Solution: The soles of the shoes have grooves to increase friction between the surface of the floor and the soles of the shoes. This prevents slipping on the floor.
     
17. Can static friction also produce heat when two bodies try to slide over one another?
    Solution: No, static friction does not result in the production of heat. Only kinetic friction creates heat. To generate heat, there must be a relative motion between the objects. For example, if you keep your hands together and move them together, no heat is generated, but if you rub them over each other, heat is generated. Heat is generated only in kinetic friction.
     
    Assertion-Reasoning Questions
    
    Below questions consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below:
     
18. Assertion: Fine powder is sprinkled on the carrom board to increase the friction.
    Reason: Friction is a self-adjusting force.
    Correct option: (d) A is false but, R is true.
    Solution: A fine powder is sprinkled on the carrom board to decrease friction so the striker can smoothly slide over the carrom surface. 
    
    
19. Assertion: Fluid friction can be reduced by giving suitable shapes to the bodies moving in it.
    Reason: Gases and liquids are called fluids.
    Correct option: (b) Both A and R are true, but R is not the correct explanation of A.
    Solution: Fluid friction can be reduced by giving a streamlined shape to objects moving in it. 
    
    Case-Based Questions
    
    
20. In a large commercial center, there are four paths to reach the main road. One of the paths has mud, the second is laid with polished marble, the third is laid with granite and the fourth has a gravel surface. It is raining heavily, and Surbhi wishes to reach the main road.
    (a) The path on which Surbhi is least likely to slip is
    (i) muddy surface
    (ii) polished marble
    (iii) granite
    (iv) gravel surface
    (b) Give a reason for the selection of the choice of option in part (a).
    (c) In which direction does the force of friction act?
    (d) What is friction?
    Solution:
    (a) Correct option: (iv) Gravel surface
    Solution: A gravel surface will provide more friction than any other path. Thus, Surbhi is less likely to slip on the gravel surface. 
    (b) Friction is caused by the irregularities on the two surfaces in contact. Gravel surfaces have many irregularities. Thus, the force of friction this surface provides will be more than any other surface.
    (c) The force of friction acts in the opposite direction to the applied force.
    (d) Friction is the force which develops at the surfaces of contact between two bodies and opposes their relative motion.