A student pulls horizontally on a 12 kg box, which then moves horizontally with an acceleration of 0.2 m/s^2. If the student uses a force of 15 N, what is the coefficient of kinetic friction of the floor?

Question

badhi · Answer

You can find the Resultant force that is applied on box since the acceleration and the mass of the box is give (take it as $F_R$)

This resultant force is generated by the force applied by the student and the Frictional force generated opposite direction to it. Since the applied force is given you can find the frictional force. Using $F_f=\mu_k R$ you can find the coefficient of kinetic friction of the floor.

anonymous · Answer

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$$15-muN = 2.4$$ 
here N = 120.on solving the equation we get coeff of friction = 0.015