A particle of mass m strikes a wall at an angle of incidence 60° with velocity V elastically. Then the change in momentum is?

1 Answer
Apr 18, 2018

#| Delta mathbf p| = 2 mV sin 60#

Explanation:

Check what is meant by "incident" angle. See drawing for one interpretation. Swap 30 for 60 if it's the optics definition.

http://electron6.phys.utk.edu

For an elastic collision we can say that:

  • #mathbf p_i = mV(( sin 60),(cos 60))#

and

  • #mathbf p_f = mV(( -sin 60),(cos 60))#

So, kinetic energy is preserved because #|mathbf V_i| = |mathbf V_f|#

#implies | Delta mathbf p| = |mV(( - 2 sin 60),(0))| = 2 mV sin 60#