Urgent Help Needed- Finding the speed at the centre of mass? Please help me

In summary, the person is seeking urgent help in finding the speed at the centre of mass after an inelastic collision between two objects with masses of 500g each. They are unsure of how to calculate the centre of gravity and momentum, and have questions about adding velocities and masses in the calculations.
  • #1
TaintedLove
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Urgent Help Needed- Finding the speed at the centre of mass? Please help me :(

Hi, I was attempting to work through this question.
Anyways, I was working from a graph, so the radius 2.5 cm, the two of them collided, it was an inelastic collision as the two objects did part ways, so how do I find the centre of gravity?
I attempted to calculate it... but if someone could help me out? The masses were 500g and 500g.

So for x and y, would I do:
Xcg = (500)(0.025) + (500)(1.5)(0.025) / 1000 ?
Ycg = (500)(0.025) + (500)(0.025) / 100 ?

That's what I was thinking but I'm not entirely sure.

After this, I also have to find the momentum of the centre of gravity... so for that, I need the masses and the speed.

Even though the objects didn't stick together, would I add the masses when solving for the momentum at the centre of mass?

I was reading on the internet and it said: "The center of mass velocity of a system of particles is the average velocity of all the particles weighted relative to their mass"

but what I'm confused about is, do I add all the velocities... like the velocities of both the masses before and after the collision? So I'd have 4 velocities? But I'd only add the masses twice right? So it would be the velocities / 1000 g

Could someone really help me. Please.
 
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  • #2


I answered your question in the other thread, but let me elaborate.

When you calculate the velocity of the center of mass, you're calculating it for a certain point in time, and the velocities that enter into the formula are those of the objects at that point in time.
 

FAQ: Urgent Help Needed- Finding the speed at the centre of mass? Please help me

1. How do I find the speed at the centre of mass?

To find the speed at the centre of mass, you will need to know the mass and velocity of each individual particle or object in the system. Then, you can use the equation v = ∑(m_i*v_i)/∑m_i, where m_i is the mass of each particle and v_i is its velocity. This will give you the speed at the centre of mass.

2. What is the importance of finding the speed at the centre of mass?

The speed at the centre of mass is important because it represents the overall motion of a system of particles. It can help determine the stability and dynamics of a system, as well as provide valuable information for solving problems in physics, engineering, and other fields.

3. Can the speed at the centre of mass change over time?

Yes, the speed at the centre of mass can change over time if there is a net external force acting on the system. This can cause a change in the overall velocity of the system, which will also affect the speed at the centre of mass.

4. How does the speed at the centre of mass differ from the average speed of the individual particles?

The speed at the centre of mass is different from the average speed of the individual particles because it takes into account the mass of each particle. The average speed only considers the velocities of the particles, while the speed at the centre of mass considers both mass and velocity.

5. Are there any other methods for finding the speed at the centre of mass?

Yes, there are other methods for finding the speed at the centre of mass, such as using the conservation of momentum or the law of angular momentum. These methods may be more appropriate for certain systems or situations, but the equation v = ∑(m_i*v_i)/∑m_i is generally the most commonly used method.

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