ELASTIC & INELASTIC Analyzing Collisions

Collisions During a collision, there is a transfer of momentum & energy. To calculate momentum = p ai + p bi = p af + p bf (remember p = mΔv) To calculate energy = KE ai + KE bi = KE af + KE bf (remember KE = ½ mv 2 )

Collisions 2 types of collisions #1 = Elastic – “hit & rebound” - momentum is conservedFor Perfectly Elastic - KE remains the same

m a v a initial m b v b initial P before = m a (+v a ) + m b (-v b ) m b v b final P after = m a (-v a ) + m b (+v b ) m a v a final

Elastic Collision Equation m a (+v a ) + m b (-v b ) = m a (-v a ) + m b (+v b ) *Positive velocity to the right *Negative velocity to the left

Collisions 2 types of collisions #2 = Inelastic – “hit & stick” - momentum is conservedFor Perfectly Inelastic - KE is decreased

Collision: hit and stick m a v a initial m b v b initial P before = m a (+v a ) + m b (-v b ) m b v b final P after = (m a + m b )(v a&b combined ) m a v a final v ab

Collision: hit and stick Inelastic Collision Equation m a (+v a ) + m b (-v b ) = (m a + m b )(v a&b combined ) *Positive velocity to the right *Negative velocity to the left