Work Power and Energy 3 Question 5

5. A block of mass 0.18kg is attached to a spring of force constant 2N/m. The coefficient of friction between the block and the floor is 0.1 . Initially the block is at rest and the spring is unstretched. An impulse is given to the block as shown in the figure. The block slides a distance of 0.06m and comes to rest for the first time. The initial velocity of the block in m/s is v=N10. Then N is

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(2011)

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Answer:

Correct Answer: 5. (4)

Solution:

  1. Decrease in mechanical energy = Work done against friction

12mv212kx2=μmgx or v=2μmgx+kx2m

Substituting the values, we get

v=0.4m/s=410m/sN=4



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