To practice Problem-Solving Strategy 8.1 Conservation of Momentum. Protecting his nest, a 600-g peregrine falcon rams a marauding 1.5-kg raven in midair. The falcon is moving at 20.0 m/s , and the raven at 9.00 m/s at the moment of impact. The falcon strikes the raven at right angles to the raven's direction of flight and rebounds straight back with a speed of 5.00 m/s . By what angle does the impact change the raven's direction of motion?

Answer :

Answer:

The angle as calculated is [tex]48.013^{\circ}[/tex]

Solution:

As per the question:

Mass of falcon, [tex]m_{f} = 600\ g =0.6\ kg[/tex]

Mass of raven, [tex]m_{r} = 600\ g =0.6\ kg[/tex]

Initial speed of the falcon, [tex]v_{f} = 20.0\ m/s[/tex]

Initial speed of the raven, [tex]v_{r} = 9.00\ m/s[/tex]

Rebounding speed of the falcon, [tex]v'_{f} = - 5\ m/s[/tex]

Now,

To calculate the angle at which the direction of motion of the raven changes:

By using the principle of conservation of momentum:

[tex]m_{f}v_{f} + m_{r}v_{r} = m_{f}v'_{f} + m_{r}v'_{r}[/tex]

[tex]0.6\times 20\hat{j} + 1.5\times 9\hat{i} = 0.6\times -5\hat{j} + 1.5v'_{r}\hat{i}[/tex]

[tex]1.5v'_{r} = 15\hat{j} + 13.5\hat{i}[/tex]

[tex]v'_{r} = 9\hat{i} + 10\hat{j}[/tex]

The angle of the change of the raven's direction is given by:

[tex]tan\theta = \frac{10}{9}[/tex]

[tex]\theta = tan^{- 1}(1.112) = 48.013^{\circ}[/tex]

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