Question

In a game of ultimate air hockey, pucks of different sizes and masses are used simultaneously. Angel has left her reach extended and Eric pounces on the opportunity by sending a puck of mass 2.0[kg] at a speed of 10.0[m/s] towards a puck of mass 5.0[kg] that is traveling at 5.0m/s] at an angle of 20.0^o from the velocity of the first puck. After the collision, the 5.0[kg] puck has a speed of 6.0[m/s] in the original direction of the 2.0[kg] puck (to the right). What is the total, initial y-component of momentum in the system? Express your answer in kg*m/s.

A 20000 kg railroad car is rolling at 1.00 m/s when a 2000 kg load of gravel is suddenly dropped in.

What is the car's speed just after the gravel is loaded?

Answer 1

Given

pucks of mass m1= 2 kg initially moving to right with velocity 10 m/s and

pucks of mass m2= 5 kg initially moving with velocity 5 m/s at an angle of 20 degrees in xy plance

after collision m2 is moving with velocity 6 m/s , in the m1 direction

initial y component of the system is , Py = ?

here the y momentum component of m1 is zero because it is moving alon x direction (right)

   so the y momentum component of, m2 is , P2y = m2*v2i sin 20 kg.m/s = 5*5 sin 20 kg.m/s = 8.55 kg.m/s

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railroad car mass m 1 = 20000 kg , initially moving with velocity v1 = 1.00 m/s

load of gravel mass m2 = 2000 kg added to car then the final speed of the car with gravel is v2= ?

from conservation of momentum

   m1*v1 = (m1+m2)v2

   v2 = m1*v1/(m1+m2)

   v2 = 20000*1/(20000+2000) m/s

   v2 = 0.909 m/s

the car's speed just after the gravel is loaded, v2 = 0.909 m/s