A 1000-kg car traveling at 66 m/s hits a 2000-kg car at rest and the two travel together after the collision. Calculate the speed with which they move.

Question

anonymous · Answer

initial momentum = final momentum
$$m_1v_1+m_2v_2=v_f(m_1+m_2)$$

anonymous · Answer

so 1000x2000 +2000x v2 =vf(3000) ???

anonymous · Answer

No, pair the masses and velocities. So 1000 kg goes with 66 m/s and 2000 kg goes with 0 m/s (since the car is at rest)
$$(1000~kg)(66~m/s)+(2000~kg)(0~m/s)=v_f(2000~kg+1000~kg)$$

anonymous · Answer

so the only variable left if $v_f$

anonymous · Answer

so its 68000/3000 which equals 22.66 right ?

anonymous · Answer

2000*0=0, so
66,000/3,000 = 22 m/s even

anonymous · Answer

Thank you very much !!

anonymous · Answer

you're welcome