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4.2 friction — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysics4.2 friction1 Mark
MCQ
A heavy box is solid across a rough floor with an initial speed of $4 \,m / s$. It stops moving after $8$ seconds. If the average resisting force of friction is $10 \,N$, the mass of the box (in $kg$ ) is .....
  • A
    $40$
  • ✓
    $20$
  • C
    $5$
  • D
    $2.5$
✓

Answer

Correct option: B.
$20$
b
(b)

Same like previous question

$\mu=\frac{4}{80}=0.05$

$F=\mu m g$

$10=0.5 \,m$

$m=20 \,kg$

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