Question 7 Two ice skaters, Daniel mass 70.0 kg and Rebecca (mass 45.0 kg), are

Question

Question 7 Two ice skaters, Daniel mass 70.0 kg and Rebecca (mass 45.0 kg), are practicing. Daniel stops to tie his shoelace and, while at rest, is struck by Rebecca, who is moving at 13.0 m/s before she collides with him. After the collision, Rebecca has a velocity of magnitude 8.00 m/s at an angle of 55. from her initial direction. Both skaters move on the frictionless, horizontal surface of the rink Part A What is the magnitude of Daniel's velocity after the collision? 6.86 m/s Subm My Answers Give Up Correct Part B What is the direction of Daniel's velocity after the collision? AE 322.06 G from the Rebecca's original direction Submit My Answers Give Up Incorrect; Try Again; 5 attempts remaining Part C What is the change in total kinetic energy of the two skaters as a result of the collision? AK 714 J Subm My Answers Give Up Correct

Explanation / Answer

mass of Daniel m2 = 70 kg, u2 =0 m/s, v2=6.86 m/s
mass of Rebecca m1 = 45 kg, u1 = 13 m/s, v1 = 8.00 m/s, and theta 1 = 55.1 degrees

from conservation of x-component of momemtum of the system

   m1u1 = m1v1 cos theta1 + m2v2 cos theta2

   cos theta2 = m1u1 - m1v1 cos theta1 /( m2v2)

       theta2 = arc cos(m1u1 - m1v1 cos theta1 /( m2v2))

                = arc cos ((45*13 - 45*8 cos 55.1) / (70*6.86))

           = 37.88 degrees

direction of Daniel velocity after collision is 37.88 degrees

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