Impulse-Momentum - Bowling ball elastic collision

[imwithdumbhead]

thanks for help. question, at 5:17, where does 208.8 come from?

[fyfadmin]

@imwithdumbhead

208.8 comes from the expansion of the terms inside the squared bracket.

(23.4 - 6V2f)^2 simplifies to

(23.4 - 6V2f)*(23.4 - 6V2f)

23.4*23.4 - 23.4*6V2f - 23.4*6V2f + 6V2f*6V2f

547.56 - 140.4V2f - 140.4V2f +36V2f^2

547.56 - 280.8V2f +36V2f^2

The -280.8V2f term comes from the two middle terms of the expansion. If you remember FOIL (first, outside, inside, last); these are the outside and inside terms.

[imwithdumbhead]

@fyfadmin clear. thanks much