Home
Class 11
PHYSICS
A block A of mass 2 kg rests on another ...

A block A of mass 2 kg rests on another block B of mass 8 kg which rests on a horizontal floor. The coefficient of friction between A and B is 0.2 while that between B and floor is 0.5. when a horizontal force of 25 N is applied on the block B. the force of friction between A and B is

A

zero

B

`3.9` N

C

`5.0` N

D

49 N

Text Solution

Verified by Experts

The correct Answer is:
A
Force of friction between B and surface is :
`f_(B) = mu_(2) (m_(1) + m_(2) ) g = 0.5 xx (2 + 8) xx 10 = 50 N`

As applied force 25 N is less than this force of friction , the system has no tendency to move . Hence , friction between A and B is zero .
Promotional Banner

Topper's Solved these Questions

  • FRICTION AND CIRCULAR MOTION

    GRB PUBLICATION|Exercise More than one correct|18 Videos

  • FRICTION AND CIRCULAR MOTION

    GRB PUBLICATION|Exercise Assertion - Reason|12 Videos

  • FRICTION AND CIRCULAR MOTION

    GRB PUBLICATION|Exercise Problem For Practice|23 Videos

  • FORCE AND NEWTONS LAWS OF MOTION

    GRB PUBLICATION|Exercise Comprehension|12 Videos

  • MOTION IN A STRAIGHT LINE

    GRB PUBLICATION|Exercise Comprehension type Queston|14 Videos

Similar Questions

Explore conceptually related problems

A block A of mass 2 kg rests on another block B of mass 8 kg which rests on a horizontal floor. The coefficient of friction between A and B is 0.2 while that between B and floor is 0.5 .When a horizontal floor F of 25 N is applied on the block B the force of friction between A and B is

A block A of mass 200 kg rest on a block B of mass 300 kg . A is tied with a horizontal string to a wall. Coefficient of friction between A and B is 0.25 and that between B and floor is 0.2 . The horizontal force F needed to move the block B is

A block A of mass 2 kg is placed over smooth block B of mass 4 kg which is placed over a smooth horizontal floor The coefficient of friction between A and B is 0.4 when a horizontal forces of magnitude 10 N is applied on A the acceleration of block of A and B are

A block of mass 2 kg is at rest on a floor . The coefficient of static friction between block and the floor is 0.54. A horizonatl force of 2.8 N is applied to the block . What should be the frictional force between the block and the floor ? ( take , g = 10 m//s^(2) )

A block A of mass m kg lies on a block B of mass m kg. B in turn lies on smooth horizontal plane. The coefficient of friction between A and B is mu . Both the blocks are initially at rest. A horizontal force F is applied to lower block B at t = 0 till the lower block B undergoes a displacement of magnitude L. Match the statements in Table-1 with the results in Table-2.

Block of mass m rests on the plank B of mass 3m which is free to slide on a frictionless horizontal surface. The coefficient of friction between the block and plank is 0.2. If a horizontal force of magnitude 2 mg is applied to the plank B, the acceleration of A relative to the plank and relative to the ground respectively, are

A small block of mass 20kg rests on a bigger block of mass 30kg , which lies on a smooth horizontal plane. Initially the whole system is at rest. The coefficient of friction between the blocks is 0.5 . The horizontal force F=50N is applied on the lower block. a. Find the work done by fricitonal force on upper block and on the lower block in t=2s . b. Is the magnitude of work done by the frictional force on upper and lower blocks same? c. Is the work done by the frictional force on the upper block converted to heat or mechanical energy or both?

GRB PUBLICATION-FRICTION AND CIRCULAR MOTION -OBJECTIVE QUESTIONS ( only one choice is correct )
  1. A body of mass 60 kg is dragged with just enough force to start movin...

    Text Solution

    |

  2. Pushing force making an angle theta to the horizontal is applied on a ...

    Text Solution

    |

  3. A block A of mass 2 kg rests on another block B of mass 8 kg which res...

    Text Solution

    |

  4. A 40 kg slab rests on a frictionless floor . A 10 kg block rests on to...

    Text Solution

    |

  5. A block of mass m lying on a rough horizontal surface of friction coef...

    Text Solution

    |

  6. A block of mass 0.1 is held against a wall applying a horizontal force...

    Text Solution

    |

  7. A lineman of mass 60 kg is holding a vertical pole . The coefficient o...

    Text Solution

    |

  8. A ball weighing 10g hits a hard surface vertically with a speed of 5m/...

    Text Solution

    |

  9. A heavy box of mass 20 kg is pulled on a horizontal surface by applyin...

    Text Solution

    |

  10. A block takes a twice as much time to slide down a 45^(@) rough incli...

    Text Solution

    |

  11. A block of mass 2 kg rests on a rough horizontal plank , the coefficie...

    Text Solution

    |

  12. A block released from rest from the top of a smooth inclined plane of...

    Text Solution

    |

  13. A block of mass 10 kg is sliding on a surface inclined at 30^(@) with ...

    Text Solution

    |

  14. A block of mass 6 kg is being pulled by force 24 N as shown . If coeff...

    Text Solution

    |

  15. Coefficient of static friction between the two blocks in Fig. 7.124 is...

    Text Solution

    |

  16. In Fig.7.125, coefficient of friction between m(1) and m(2) is mu and ...

    Text Solution

    |

  17. If, in Q.19, coefficient of friction between m(1) and the wall is mu,a...

    Text Solution

    |

  18. The rear side of a truck is open and a box of 40 kg mass is placed 5 m...

    Text Solution

    |

  19. Three blocks are kept as shown in figure Acceleration of 20 kg block w...

    Text Solution

    |

  20. Two block of masses m1 and m2 are connected with a massless unstretche...

    Text Solution

    |