Q. A wooden box of mass 8 kg slides down an inclined plane of inclination 30${^\circ}$ to the horizontal with a constant acceleration of $0.4\ ms^{- 2}$. What is the force of friction between the box and inclined plane? [$\ g = 10\ ms^{- 2}$]

A) 36.8 N
B) 76.8 N
C) 65.6 N
D) 97.8 N
Explanation

(a) $ma = mg\sin{\theta - f}$
or $f = mg\sin{\theta - ma}$
$= 8\left\lbrack 10 \times \frac{1}{2} - 0.4 \right\rbrack$ N = 8$\times 4.6$N = 36.8 N

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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