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Work,energy ratio

  • Thread starter alijan kk
  • Start date
  • #1
130
5

Homework Statement



4. Two bodies of mass m1 and m2 have equal momentum their kinetic energies E1 and E2 are in the ratio.

ans. m2 : m1[/B]


Homework Equations


E1=E2
P= mv

The Attempt at a Solution



E1=E2
1/2M1v^2=1/2M2v^2
(Mv^2)/2=(M2v^2)/2
multiply both side by 2
mv^2=2(m2v^2)/2
mv^2= m2v^2

what should i do now? or the attemp is full wrong.
 

Answers and Replies

  • #2
201
51
Your attempt is wrong. How did you get E1 = E2?

By the given question we have equal momentum [itex] m_1v_1 = m_2v_2 [/itex] We have to find out the ratio [itex] \frac{\frac{1}{2}m_1v^2_1}{\frac{1}{2}m_2v^2_2} [/itex] . Try to get the second ratio using the first equation.
 
  • #3
130
5
Your attempt is wrong. How did you get E1 = E2?

By the given question we have equal momentum [itex] m_1v_1 = m_2v_2 [/itex] We have to find out the ratio [itex] \frac{\frac{1}{2}m_1v^2_1}{\frac{1}{2}m_2v^2_2} [/itex] . Try to get the second ratio using the first equation.
i dont know how to get the second ratio
 
  • #4
201
51
i dont know how to get the second ratio
Well notice how you have to get [itex]v^2_1[/itex] and [itex]v^2_2[/itex] . So first off you square both sides and then try to remove the extra [itex] m_1 [/itex] and [itex]m_2[/itex]
 
  • #5
130
5
Well notice how you have to get [itex]v^2_1[/itex] and [itex]v^2_2[/itex] . So first off you square both sides and then try to remove the extra [itex] m_1 [/itex] and [itex]m_2[/itex]
i got

m1v^2=m2v^2 right?

should i square both side now
 
  • #6
201
51
i got

m1v^2=m2v^2 right?
By squaring the equation you should get [itex] m^2_1v^2_1 = m^2_2v^2_2 [/itex]
 
  • #7
130
5
By squaring the equation you should get [itex] m^2_1v^2_1 = m^2_2v^2_2 [/itex]
how can i get :-'
 
  • #8
130
5
give me the equation that i should try to solve
 
  • #9
201
51
Well using the equation [itex] m^2_1v^2_1 = m^2_2v^2_2 [/itex] you should get [itex] \frac{m_1v^2_1}{m_2v^2_2} = \frac{m_2}{m_1} [/itex]
 
  • #10
haruspex
Science Advisor
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give me the equation that i should try to solve
In your original attempt your very first equation was wrong. You wrote E1=E2. As Mastermind explained, that is not what you are given. You are given p1=p2, where pi=mivi. I see no evidence that you have understood that.
Start again with the given information and show all your steps. Do not write "I got ...".
 

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