A boxcar of length 8.00 m and height 2.40 m is at rest on frictionless rails. Th

Question

A boxcar of length 8.00 m and height 2.40 m is at rest on frictionless rails. The empty boxcar has a mass of 3250 kg. Inside the boxcar, located at the left end, is a tank containing 1700 kg of water. The tank is 1.30 m long and 2.40 m tall. The tank starts to leak, and the water fills the floor of the boxcar uniformly. Assume that all the water stays in the box car. After all the water has leaked out of the tank, what will be the final velocity of the boxcar? (Take movement to the right as positive.)

Explanation / Answer

Shift is potential energy of the water is the cause for the velocity to the boxcar.

Initially, center of mass of water in the tank is at 1.3/2 = 0.65 m

Volume of water is same ; 1.3 * 2.4 * b = 8 * b * H

H = 0.39 m

Center of mass will be now at 0.195 m.

Change in height = 0.65-0.195 = 0.455 m.

Decrease in potential energy = increase in kinetic energy

m g h = 0.5 * ( m +M) V^2

1700 * 9.8 * 0.455 = 0.5 * (3250+1700) * V^2

V =1.75 m/s

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.