A railway car having a total mass of 5.8 $\times$10⁵ kg,moving with a speed of 9.1 km/h,strikes another car that has a mass of 8.7 $\times$ 10⁵ kg and is initially at rest.The speed of the coupled cars after the collision is A)9.1 km/h B)7.2 km/h C)3.6 km/h D)1.8 km/h E)4.2 km/h

Question

Quizplus · Accepted Answer

We can use the conservation of momentum to solve this problem. Before the collision, the total momentum of the system is:

p1 = m1*v1 + m2*v2

where m1 and v1 are the mass and velocity of the first car, m2 and v2 are the mass and velocity of the second car. Since the second car is initially at rest, v2 = 0. Substituting the given values, we have:

p1 = (5.8*10^5 kg)*(9.1 km/h) = 5.278*10^8 kg*m/h

After the collision, the two cars will move together with the same velocity v:

p2 = (m1 + m2)*v

where m1 + m2 is the total mass of the system. Substituting the given values, we have:

p2 = (5.8 + 8.7)*10^5 kg * v

Equating p1 and p2, we can solve for v:

5.278*10^8 kg*m/h = (5.8 + 8.7)*10^5 kg * v

v = 3.6 km/h

Therefore, the speed of the coupled cars after the collision is 3.6 km/h, which corresponds to answer choice C.

A Railway Car Having a Total Mass of 5 ×\times× 105 Kg,moving with a Speed of 9

A Railway Car Having a Total Mass of 5 $\times$ 10⁵ Kg,moving with a Speed of 9