Question

Trolley A of 200 grams moving at 1.5m/s to the right collides with a stationary Trolley B. Trolley B weighs 100 grams more than Trolley A. After the collision they move off together.$Calulate the velocity that they move off.$ Include units in your answer. You may use the equation mass =$momentum/velocity.$ no copied answers wrong answers will be reported

Answer 1

Answer:

Mass of the trolley, M=200kg

Speed of the trolley, v=36km/h=10m/s

Mass of the boy, m=20kg

Initial momentum of the system of the boy and the trolley

     =(M+m)v 

     =(200+20)×10

     =2200kg m/s

Let v′ be the final velocity of the trolley with respect to the ground.

Final velocity of the boy with respect to the ground  =v′−4

Final momentum =Mv′+m(v′−4)

                             =200v′+20v′−80

From the conservation of linear momentum:

Initial momentum= Final momentum

                  2200=220v′−80

                    ∴ v′=2280/220=10.36m/s

Length of the trolley, l=10m

Speed of the boy, v′′=4m/s 

Time taken by the boy to run, t=10/4=2.5s

∴ Distance moved by the trolley =v′′×t= 10.36×2.5=25.9m