Question

Peregrine falcons are the fastest birds in the world, reaching max- imum speeds of up to 320 km/h (88 m/s) during a hunting stoop. In one such episode, a 600-g falcon traveling at its top speed hits a 458-g pigeon flying east. The falcon, also flying directly east hits the pigeon from directly behind.The falcon grabs the pigeon with its talons and the pair travels together at a speed of 65 m/s. What is the energy lost in the collision? (Hint: the total initial kinetic energy is not just the falcon's kinetic energy; assume that the height of the birds does not change during the collision)

Answer 1

Answer:

366.6J

Explanation:

We only need to apply conservative linear momentum, making v the initial speed of pigeon, so

$m_1v_1+m_2v_2 = (m_1+m_2)V$

$600g*88m/s+458g*v_2 = (600+458)*65m/s$

Solving for v,

$v_2 = 34.87m/s$

The energy lost we can calculate with

$KE_{lost} = \frac{1}{2}m_1v_1^2+\frac{1}{2}m_2v_2^2-\frac{1}{2}(m_1+m_2)V^2$

$KE_{lost} = \frac{1}{2}*0.6*88^2 + \frac{1}{2}*0.458*34.87^2 - \frac{1}{2} (0.6+0.458)*65^2$

$KE_{lost} = 366.6J$