Mary and her sister are playing with a cardboard box on the neighborhood hill. Mary climbs into the box, the total mass of the box with Mary in it is 115 kg. The box starts at rest at the beginning of the incline. The hill is at an incline of 28 degrees with respect to the horizontal.The static and kinectic friction between the box and hill is 0.4 and 0.2 respectively. Assume that Mary is now in the box, but has not started to move. a. What is the magnitude of the friction force acting on the box? b. What is the magnitude of the net force acting on the box and child system? c. Will the box slide down the hill, or stay at rest?

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Static and Kinetic Friction

Kinetic friction comes into existence when there are moving surfaces means in other words we can say that the force which comes into existing between moving surfaces is known as kinetic friction.