Question

a loaded fed - ex truck has a mass of 2000 kg and travels at 30 m/s. the door accidentally opens and the packages fell out. the mass is now 1500 kg. what is the change in momentum?

a 60,000 kg m/s
b 15,000 kg m/s
c - 15,000 kg m/s
d 45,000 kg m/s

Explanation:

Step1: Calculate initial momentum

Momentum formula is \(p = mv\). Initial mass \(m_1=2000\space kg\), velocity \(v = 30\space m/s\). So initial momentum \(p_1=m_1v=2000\times30 = 60000\space kg\cdot m/s\)

Step2: Calculate final momentum

Final mass \(m_2 = 1500\space kg\), velocity \(v = 30\space m/s\) (velocity remains same as no external force in horizontal direction). So final momentum \(p_2=m_2v=1500\times30=45000\space kg\cdot m/s\)

Step3: Calculate change in momentum

\(\Delta p=p_2 - p_1\). Substitute values: \(\Delta p=45000 - 60000=- 15000\space kg\cdot m/s\)

Answer:

C. -15,000 kg m/s