Heavy mass vs light mass in circular motion

In summary, when the masses are the same, gravity is what keeps the spheres from moving away from each other.
  • #1
technotux
1
0
Homework Statement
If I have 2 spheres with different mass in a spinning Y shaped tube(no water is in the tube),
https://i.stack.imgur.com/KG7E7m.png
https://i.stack.imgur.com/GE79gm.png

which one will go higher because of inertia and centripetal force, the light sphere or the heavy sphere?

Or if I have 2 masses, a light one and a heavy one on opposite sides but at the same distance from the centre of a spinning table, which mass will move farther from the centre the heavy one or the light one?
https://i.stack.imgur.com/vM5ztm.png
Relevant Equations
f=ma
a=(V^2)/r
i think that the light sphere will go up higher(will have bigger acceleration) because there has to be a balance between the mass and the acceleration as long as the force is the same,

for example if you push a heavy object and with the same force pushed another light object the light object will travel farther(will have more acceleration): let us assume the force=2N, and mass A=4kg, mass B=2kg,

acceleration of mass(A)
aA=fm=24=0.5m/s2

acceleration of mass(B)
aB=fm=22=1m/s2

But in a centrifuge, denser substances and particles in the solution move outward in the radial direction. At the same time, objects that are less dense move to the centre?
 
Last edited:
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  • #2
technotux said:
as the force is the same,
What force is the same?
 
  • #3
Welcome!
For the forst two cases, gravity is limiting the movement of the masses.
What is doing so for the third case?
 
  • #4
The reason why the two beads on the Y-shaped contraction settle where they do is different from the reason why particles in a centrifuge settle where they do in the sense that different mechanisms are at work for reaching dynamic equilibrium. Consider the first case. For a bead to move around in a horizontal circle, there must be no net vertical force. You know that the Earth exerts a down force which is proportional to the mass of each bead. Therefore there must be an "up" force acting on each bead to cancel the down force of the Earth. Clearly that force must be greater on the heavier bead. Where does this force come from? How does it happen that gravity is matched precisely and separately for each bead? It can all be done with Fnet = ma and a free body diagram.
 
  • #5
technotux said:
i think that the light sphere will go up higher(will have bigger acceleration) because there has to be a balance between the mass and the acceleration as long as the force is the same,
If the force spinning the y-tube has a magnitude of 3, and the spheres have masses of 1 and 2, how much force is being applied to the spheres added up ? separately ? Remember Newton.
 

FAQ: Heavy mass vs light mass in circular motion

What is the difference between heavy mass and light mass in circular motion?

The main difference between heavy mass and light mass in circular motion is their inertia, or resistance to change in motion. Heavy mass has a greater inertia, meaning it requires more force to change its speed or direction compared to a lighter mass. This is due to the fact that heavy mass has more mass and therefore more gravitational pull.

How does the mass of an object affect its circular motion?

The mass of an object affects its circular motion by determining its inertia. As mentioned before, a heavier mass has a greater inertia and therefore requires more force to change its motion. This means that a heavier mass will have a larger radius of curvature and a slower speed compared to a lighter mass in circular motion.

Can a light mass and a heavy mass have the same circular motion?

Yes, a light mass and a heavy mass can have the same circular motion if they have the same angular velocity, or rate of rotation. This means that they will complete one full rotation in the same amount of time, even though they have different masses. However, the heavier mass will require more centripetal force to maintain this motion compared to the lighter mass.

How does the force on an object change if its mass is increased in circular motion?

If the mass of an object is increased in circular motion, the force on the object will also increase. This is because the object's inertia has increased, and therefore more force is needed to maintain its circular motion. This is why objects with a heavier mass require more centripetal force to stay in circular motion compared to objects with a lighter mass.

Why is it easier to change the direction of a light mass compared to a heavy mass in circular motion?

It is easier to change the direction of a light mass compared to a heavy mass in circular motion because of its lower inertia. Lighter masses require less force to change their direction compared to heavier masses, which have a greater resistance to change. This is why objects with a lighter mass can make sharper turns and have a smaller radius of curvature compared to objects with a heavier mass in circular motion.

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