A heavy box is solid across a rough floor with an initial speed of 4 ,m / s . It stops moving after

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4-2.Friction

easy

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

$40$

B

$20$

C

$5$

D

$2.5$

Solution

(b)

Same like previous question

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

$F=\mu m g$

$10=0.5 \,m$

$m=20 \,kg$

Standard 11

Physics

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