If an 800.0 Kg sports car slows to 8.0 m/s in the forward direction to check out an accident scene and a 1200.0 kg pick-up truck behind them continues traveling at 15.0 m/s forward, with what velocity will the two move if they lock bumpers after a rear-end collision

Explanation:

Step one:

given data

mass m1=800kg

velocity v1=8m/s

mass m2= 1200kg

velocity v2=15m/s

Note: the two bodies move with the same velocity after collision, hence the common velocity is v=?

Step two:

the expression for the total momentum is

m1v1+m2v2=v(m1+m2)

substituting we have

800*8+1200*15=v(800+1200)

6400+18000=v(2000)

24400=2000v

divide both sides by 2000 to find v

v=24400/2000

v=12.2m/s

Their common velocity is 12.2m/s

newton's first law of motion

it would be kevlar ^^