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A block of mass 100 kg slides over a distance of 10 m on a horizontal surface. If the co-efficient of friction between the surfaces is 0.4, then the work done against friction (in J) is

Asked in JEE Main 29th Jan 1st Shift 2024 · Work done by friction

• (1) 4200
• (2) 4000
• (3) 4500
• (4) 3900

Step-by-step solution

Why the other options are wrong

• (1) No single slip gives 4200 J. Sanity check: μ N d with N=1000 N is exactly 4000 J.
• (3) No single slip gives 4500 J; it would need μ=0.45.
• (4) No single slip gives 3900 J; with g=9.8 the answer would be 3920 J, which is not this option either.

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