Physics Help!!!!!

Question

A 2.03 kg book is placed on a flat desk. Suppose the coefficient of static friction between the book and the desk is 0.582 and the coefficient of kinetic friction is 0.316 . How much force is needed to begin moving the book?

How much force is needed to keep the book moving at constant speed once it begins moving?

Answer 1

On a flat, horizontal surface, weight is equal to the normal reaction R.

Minimum force needed to move a stationary object is equal and opposite to the frictional force F_f.

Frictional force F_f = µR

∴ F_f = 0.582 x 2.03 x 9.81 (coefficient of static friction applies in this case).

Once you make your calculator go to work for you, you should find the value of force in N.

Once the book is in motion, coefficient of kinetic friction applies

So use the same expression as before but instead of 0.582, use 0.316, the coefficient of kinetic friction.

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Mr. A.