Answer:
a)
And we need a force
Explanation:
Part a
For this case we have the following forces illustrated on the figure attached.
If we analyze on the x axis we just have two forces, fr the friction force and F the force to mantain the movement.
So we need this condition to satisfy the movement:
If we analyze the forces on the y axis we have this:
Because we have constant speed for this reason the acceleration is 0
And by definition the friction force is defined as:
So then the friction force would be:
And we need a force
Part b
For this case we assume that F =0 and we have a friction force of 32.928 N.
From the second law of Newton we have:
vf =0 (final velocity, rest at the end) and vi = 3.5 m/s.
And we can find the time for the motion like this:
And then we can find the distance from the following formula: