Frictional forces of pushing a box

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In summary: So in summary, a stockroom worker pushing a box with a mass of 11.2 kilograms on a horizontal surface with a constant speed of 3.5 m/s must apply a force of 22N to maintain the motion, and if that force is removed, the box will decelerate with an acceleration of -1.96 m/s^2 until it comes to rest after traveling a distance of 3.1 meters. This can be found using kinematics equations or energy methods.
  • #1
hsestudent
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Frictional forces [SOLVED]

Homework Statement


A stockroom worker pushes a box with mass 11,2 kilograms on a horizontal surface with a constant speed of 3.5 m/s. The coeffisient of kinetic fricion between the box and the surface is 0.2.

In a) i had to find the force that the worker must apply to maintain the motion.

b) If the force calculated in part a) is removed, how far does the box slide before coming to rest.


Homework Equations





The Attempt at a Solution


I am pretty sure that I solved task a). I found the frictionforce to be 22N, and since the box is having a constant speed, the sum of forces in x-direction have to be zero.
Force = Frictionforce in this case.

But i really need some tips on the B part. Anyone?

Thanks!
 
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  • #2
Once you remove the applied force of the push, the net force is no longer zero: You have the unbalanced friction force acting to slow the box down. Find the acceleration and use kinematics to find the distance. Or use energy methods.
 
  • #3
Well the force that was being applied only acted to keep the box moving at 3.5m/s so when it is removed the box will start deccelerating from this initial speed.

You need to find the acceleration of the box due to the frictional force, which is dependant on the boxes mass. With this you can determine the distance the box travels.
 
  • #4
Thanks for fast replies:) Ok, I tried something like that, but I didn't come out with an correct answer. When the force is removed I have:

Force-Friction = ma

0 - Friction = ma

a = Friction / m = -1.96m/s^2

But how do I find the distance now?
 
  • #5
It's a kinematics problem now. Accelerated motion.
 
  • #6
Thanks

Doc Al said:
It's a kinematics problem now. Accelerated motion.

I did of course make a mess of things with the sign. Got the distance to be 3,1 meters after finding the time 1.78s.
 
  • #7
Sounds good.
 

Related to Frictional forces of pushing a box

What is frictional force?

Frictional force is the force that opposes the motion of an object when it is in contact with another surface.

What factors affect the frictional force of pushing a box?

The factors that affect frictional force include the roughness of the surface, the force pressing the two surfaces together, and the type of material the surfaces are made of.

How can the frictional force of pushing a box be reduced?

The frictional force of pushing a box can be reduced by using lubricants, such as oil or grease, between the surfaces. Additionally, using wheels or sliders instead of sliding the box directly on a surface can also reduce friction.

What is the difference between static and kinetic friction?

Static friction is the force that prevents an object from moving when a force is applied to it, while kinetic friction is the force that opposes the motion of an already moving object.

How does the weight of the box affect the frictional force?

The weight of the box does not directly affect the frictional force, but it does affect the normal force, which is the force pressing the two surfaces together. A heavier box will have a greater normal force, resulting in a greater frictional force.

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