My bill at Office Depot came to $92.35 before my teacher discount. Once the clerk applies
2 answers:
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Answer:
Explanation:
Conceptual analysis
To solve this problem we apply Newton's second law:
The acceleration of an object is proportional to the force F acting on it and inversely proportional to its mass m.
a = F / m
Where,
F = m * a Formula (1)
F: Force in Newtons (N)
m: mass in kg
a: acceleration in m/(s^2)
a = v / t Formula (2)
v: speed in m/s
t: time in seconds (s)
Known information
We know the following data:
m = 1kg
v = 1 m/s
t = 1s
Development of the problem:
In the Formula (2):
In the Formula (1):
The box is kept in motion at constant velocity by a force of F=99 N. Constant velocity means there is no acceleration, so the resultant of the forces acting on the box is zero. Apart from the force F pushing the box, there is only another force acting on it in the horizontal direction: the frictional force 
which acts in the opposite direction of the motion, so in the opposite direction of F.
Therefore, since the resultant of the two forces must be zero,
so
The frictional force can be rewritten as
where
, 
. Re-arranging, we can solve this equation to find 
, the coefficient of dynamic friction:
Therefore, since the resultant of the two forces must be zero,
so
The frictional force can be rewritten as
where