Move a mass on frictionless surface in a vacuum chamber

  • #1

Main Question or Discussion Point

How much energy is necessary to move one kilogram of mass horizontally for one meter on a perfectly frictionless surface inside a vacuum chamber?

Assuming the initial velocity of the mass is zero, the mass is at rest.
 

Answers and Replies

  • #2
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How much energy is necessary to move one kilogram of mass horizontally for one meter on a perfectly frictionless surface inside a vacuum chamber?

Assuming the initial velocity of the mass is zero, the mass is at rest.
What are your thoughts on this?
 
  • #3
What are your thoughts on this?
I guess the energy needed will depend on the time you want the mass to take to move that one meter. If you use little energy, the one kilogram mass will accelerate less and will take more time to move one meter. The more energy you use, more the one kilogram mass will accelerate, and it will take less time to move one meter horizontally.

But I wonder if there is a minimal bound in how much energy is needed to make the one kilogram mass start to move from rest on an frictionless horizontal surface in a chamber with no air resistance.

If you apply a very small force (micronewtons) for just a very brief moment (microsseconds) will that be enough to move the one kilogram mass from rest? Will it start to move horizontally in a frictionless environment, even if in a very slow speed?
 
  • #4
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If you apply a very small force (micronewtons) for just a very brief moment (microsseconds) will that be enough to move the one kilogram mass from rest? Will it start to move?
What is the net force on the object? What does Newton's second law say about this situation?

After you're done applying this small force for a short time.... what does Newton's first law say about the motion of the object?
 
  • #5
The object is at rest and the only force applied is this small force for a small amount of time, in a direction parallel to the ground.

What I really want to know is: in this case, will the mass of the object have any effect on the energy necessary to move the object one meter in a given period of time?

For example: in the same vacuum chamber with no air resistance and with perfectly frictionless surface, we put two objects of the same volume and shape, but with different densities, so one of them weights one kilogram, and the other weights 20 kilograms. Considering no friction at all (not even from air) and horizontal movement (in relation to gravity, that is: not "against" gravity and not in the direction of gravity, but neutral), and supposing we want to move the two objects one meter in 10 seconds, will it be necessary to use more energy to move the 20 kg object than the 1 kg object?

That's my doubt.
 
  • #6
jbriggs444
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The object is at rest and the only force applied is this small force for a small amount of time, in a direction parallel to the ground.

What I really want to know is: in this case, will the mass of the object have any effect on the energy necessary to move the object one meter in a given period of time?
What is the smallest number greater than zero?
 
  • #7
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What I really want to know is: in this case, will the mass of the object have any effect on the energy necessary to move the object one meter in a given period of time?
That is a different question than you asked in your first post. To answer this one you'll want to consider the speed of the object as it passes the one meter point, and what that says about its kinetic energy.
 

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