How Do You Determine the Inertia of Cart A?

[emily081715]

Looks good so far!

by using what i did earlier i get the mass of cart A as 2.1 kg

 

[emily081715]

p=mv

pi=pf

m1v+m2v=m1v+ m2v

1(0)+m2(4)=m1(4.2)+m2(2)

-4.2 =m2(2-4)

 

[berkeman]

p=mv

pi=pf

m1v+m2v=m1v+ m2v

1(0)+m2(4)=m1(4.2)+m2(2)

-4.2 =m2(2-4)

Almost there...

 

[berkeman]

And BTW, there is a good visual way to check your final answer. Can you take a guess at what it is?

 

[emily081715]

what step have i missed? solving the rest of the equation i get an answer of 2.1 kg

 

[berkeman]

what step have i missed? solving the rest of the equation i get an answer of 2.1 kg

I don't think you missed anything, and based on a visual inspection of the graph, that looks to be the correct answer. Why can I tell that with a visual inspection?

 

[emily081715]

I don't think you missed anything, and based on a visual inspection of the graph, that looks to be the correct answer. Why can I tell that with a visual inspection?

the answer should've been 2.50

 

[berkeman]

the answer should've been 2.50

Interesting. I could see maybe 2.2 if the estimate of v=4.2 should be v=4.4 instead, but to get all the way up to 2.5m/s would take something else.

Maybe we have to take the decreasing velocity due to friction into account. What is the full problem statement exactly?

 

[SammyS]

I estimated something like 2.55 to 2.7 kg .

 

[I like Serena]

Hi emily081715!

Yes. We can see that the momentum of both carts decrease at a constant rate throughout.
So what's the total momentum before the collision, what's the momentum after the collision, and how much momentum did we lose during the collision?

 

[jbriggs444]

As a result of the collision, cart A lost momentum and the standard cart gained momentum. Can you look at the graph and determine how much less momentum cart A had as a result of the collision than it would have had if the collision had not taken place?

 

[Simon Bridge]

Emily has other, more basic, problems that should be tackled before this one... get the basics down first.
Recommend anyone trying to help takes a look at past threads by this member first.

 

[I like Serena]

Hi Simon Bridge,

I don't get what you mean.
Just from Emily's previous posts in this thread she seems the have a firm grasp on the total momentum, and on setting up equations and solving them.
The one thing missing is the loss due to friction - for which she did not get a clear response.
And her request to break it down went unanswered.

 

[berkeman]

Hi Simon Bridge,

I don't get what you mean.
Just from Emily's previous posts in this thread she seems the have a firm grasp on the total momentum, and on setting up equations and solving them.
The one thing missing is the loss due to friction - for which she did not get a clear response.
And her request to break it down went unanswered.

The problem apparently is that she re-posted this question after she did not get enough hand-holding in her first thread attempt, and I took the bait. The problem turned out to be more complicated than I expected when I first replied, which is fine, but it would have been good if I hadn't wasted so much time assuming it was a simple question when the OP knew already that it was not.

Thread closed.