Suppose there is on object of 20.0kg sliding to the right. A person exert a force of 30N left on the object. The object has an acceleration of 2.5m/s^2 left. What is the magnitude and direction of kinetic friction?
Since the object is moving to the right (slowing down), I supposed the kinetic friction is to the left since it always opposes the direction of motion.
Take right to be positive.Thus, (-F) + (-30) = (20.0)(-2.5), -F = (-50) + (30), F = +(20N)
But isn't +20N mean the direction is right?
I'm a bit confused here.