Question

Need help!!
Mr. Tang is applying a force of 100 N [right] on a 5.0 kg box on a table and Haris is applying force on the box to the left. When the boxis moving, friction acts in the opposite direction of the motion and has a magnitude of 10 N. For each of the following situations, draw a FBD
and determine the magnitude of Haris’s force if:
a) the box is moving to the left at a constant velocity of 2.0 m/sb) the box is moving to the right at a constant velocity of 2.0 m/s
c) the box is moving to the left and accelerating at 1.0 m/s2 [left]d) the box is moving to the right and accelerating at

Answer 1

put up your drawing and you will be helped

Answer 2

Please use the first law of Dynamics.
We have a rectilinear motion with constant v, when on our object the vector sum of all forces acting on it is zero, so:
a)

\[\Large F = ...Newtons\]
b)

\[\Large F = ...Newtons\]
In both cases above F is the force applied to our box
Case c)
we have to apply the second law of Newton, so we have:

in that case we have:
\[\Large \vec F + \vec R = \left( {m \cdot a} \right)\hat y\]
or taking the scalr product between those vector F and R with the unit vector y, we have:
\[\Large F - R = m \cdot a\]