A railroad handcar is moving along straight, frictionless tracks with negligible

Question

A railroad handcar is moving along straight, frictionless tracks with negligible air resistance. In the following cases, the car initially has a total mass (car and contents) of 190 kg and is traveling east with a velocity of magnitude 4.60 m/s . Find the final velocity of the car in each case, assuming that the handcar does not leave the tracks.

1- An object with a mass of 23.0 kg is thrown sideways out of the car with a speed of 1.50 m/s relative to the car's initial velocity.

2- An object with a mass of 23.0 kg is thrown backward out of the car with a velocity of 4.60 m/s relative to the initial motion of the car.

3- An object with a mass of 23.0 kg is thrown into the car with a velocity of 6.40 m/s relative to the ground and opposite in direction to the initial velocity of the car.

Explanation / Answer

initial momentum of (car + contents) = 190*4.6 = 874 kg.m

1)

There is no reactive force in the east-west direction if the 23.0kgs were thrown out at an exact right angle. The velocity should not have changed.

2)

final momentum = (190-23)*v - 23*4.6

conservation of momentum

initial momentum = final momentum

874 = (190-23)*v - 23*4.6

v = (874 + 23*4.6)/(190-23) = 5.867 m/s

3)

conservation of momentum

initial momentum = final momentum

874 + 23*(-6.4) = (190+23)*v

v = (874 - 23*6.4)/(190+23) = 3.41 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.