Bird Collision Problem

  • Thread starter mnafetsc
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  • #1
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Homework Statement



To protect their young in the nest, peregrine falcons will fly into birds of prey (such as ravens) at high speed. In one such episode, a 620 g falcon flying at 20.0 m/s hit a 1.40 kg raven flying at 9.0 m/s. The falcon hit the raven at right angles to its original path and bounced back at 5.0 m/s. (These figures were estimated by the author as he watched this attack occur in northern New Mexico.)

A.By what angle did the falcon change the raven's direction of motion?
B.What was the raven's speed right after the collision?

Homework Equations


P=mv

conservation of momentum


The Attempt at a Solution



I put the falcon on the y axis and the raven on the x axis, I ten tried to find the a and y components of p then did theta= arctan9p2/p1) which gave me 45 degrees-wrong

I then tried to find the x and y components using
m_F_v_Fi + m_R_V_Ri = m_F_v_Ff + m_R_V_Rf

Solving for v_Rf for the x and y compents I got 9 and 8.16 respectively, the had theta= arctan(8.16/9)= 42 degrees again wrong.
 

Answers and Replies

  • #2
HallsofIvy
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Homework Statement



To protect their young in the nest, peregrine falcons will fly into birds of prey (such as ravens) at high speed. In one such episode, a 620 g falcon flying at 20.0 m/s hit a 1.40 kg raven flying at 9.0 m/s. The falcon hit the raven at right angles to its original path and bounced back at 5.0 m/s. (These figures were estimated by the author as he watched this attack occur in northern New Mexico.)

A.By what angle did the falcon change the raven's direction of motion?
B.What was the raven's speed right after the collision?

Homework Equations


P=mv

conservation of momentum


The Attempt at a Solution



I put the falcon on the y axis and the raven on the x axis, I ten tried to find the a and y components of p then did theta= arctan9p2/p1) which gave me 45 degrees-wrong
Precisely how did you get that? Are you assuming a perfectly elastic collision? That's probably not correct. What percentage inelasticity are you assuming?

I then tried to find the x and y components using
m_F_v_Fi + m_R_V_Ri = m_F_v_Ff + m_R_V_Rf

Solving for v_Rf for the x and y compents I got 9 and 8.16 respectively, the had theta= arctan(8.16/9)= 42 degrees again wrong.
 
  • #3
14
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Pretty much I did p=sqrt(p_1_^2 +p_2_^2

But I realize that is wrong because its not elastic situation, I know is inelastic, but not perfectly inelastic so I used the second equation thinking that would work, I'm not quite sure were to go from there.
 
  • #4
14
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Never mind I was doing it correctly, I just kept making some unknown calculation error that kept giving me the wrong angle.
 

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