Question

An open train car, with a mass of 2150 kg, coasts along a horizontal track at the speed 2.29 m/s. The car passes under a loading chute and, as it does so, gravel falls vertically into it for 2.67 s at the rate of 441 kg/s. What is the car's speed after the loading is completed? Ignore rolling friction

Answer 1

The mass of gravel is
m2=441•2.67 = 1177.47 kg

The law of conservation of linear momentum
m1•v1= (m1+m2)v2
v2= m1•v1/(m1+m2) =
=2150•2.29/(2150+1177.47)=1.48 m/s