Mary applies a force of 70 N to push a box with an acceleration of 0.50 m/s2. When she increases the pushing force to 78 N, the
box's acceleration changes to 0.68 m/s2. There is a constant friction force present between the floor and the box.
(a) What is the mass of the box in kilograms?
(b) What is the coefficient of kinetic friction between the floor and the box?
(a) What is the mass of the box in kilograms?
(b) What is the coefficient of kinetic friction between the floor and the box?
2 answers:
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1) 9.57 N
We have two forces applied on the apple:
- The force of gravity, in the downward direction:
W = 9.42 N
- The force exerted by the wind, in the horizontal direction (to the right):
Fw = 1.68 N
The two forces are perpendicular to each other, so we can find the magnitude of the net force by using Pythagorean's theorem.
Therefore, we have:
2)
The direction of the net external force, measured from the downward vertical, can be measured using the following formula:
where
is the force in the horizontal direction
is the force in the vertical direction
In this problem,
and so we find: