2. Questions Bank
  3. 8th Class
  4. Science
  5. Friction

8th Class Science Friction Question Bank Friction IIT JEE Objective Problems

  • question_answer
    The given figure shows three identical carom boards labeled I, II, and III. Sand particles have been poured on board I and oil has been poured on board II.
    Equal forces are applied on three identical pucks on the three carom boards such that their speeds on the three carom boards are \[{{v}_{1}},{{v}_{2}}\]and \[{{v}_{3}}\] respectively. The relation among the speeds of the pucks on the three carom boards is

    A)  \[{{v}_{1}}>{{v}_{3}}>{{v}_{2}}\]                             

    B)  \[{{v}_{1}}<{{v}_{3}}<{{v}_{2}}\]

    C)  \[{{v}_{1}}>{{v}_{2}}>{{v}_{3}}\]             

    D)  \[{{v}_{1}}<{{v}_{2}}<{{v}_{3}}\]

    Correct Answer: B

    Solution :

      The speed of a puck is inversely proportional to the magnitude of the frictional force acting between it and the surface of the carom board. Since the presence of sand increases the force of friction between the board and the puck, the speed of the puck on board III i.e.,\[{{v}_{3}}\]will be greater than the speed of the puck on board I i.e.,\[{{v}_{1}}\]. The oil poured on carom board II decreases the force of friction between the board and the puck. Hence, the speed of the puck on board II will be the highest i.e., \[{{v}_{1}}<{{v}_{3}}<{{v}_{2}}\] The correct answer is B.


You need to login to perform this action.
You will be redirected in 3 sec spinner