Question

1.A7.5 kg box is pushed by a person at a constant 5.0 m/s across a rough floor where the surface exerts a folfriction of 15 N on the box. The person reduces the force of their push to 10 N and continues pushing until the box come to a stop.a.Draw three qualitative graphs (position, velocity, acceleration vs. time), FBD, and force diagram when tperson has reduced their force.

Answer 1

Let t=0 represent the moment when the person reduces its force to 10N.

In that moment, the forces acting over the box are shown in the diagram:

The free body diagram for this object is:

Assuming that the initial velocity is 5.0 m/s towards the right, the net force acting on the box is 5N towards the left. Then, the box wil decelerate until it comes to a stop.

The acceleration of the box is constant and negative, until the box stops and the acceleration is 0.

The velocity of the box is 5.0m/s initially, and it decreases linearly until it reaches 0.0 m/s.

The position of the box grows as a quadratic function of time until it reaches a maximum displacement and then it stops.

These qualitative graphs, force diagram and free body diagram correspond to the described situation.