What will happen to the momentum of the car as sand is loaded onto it? & What will happen to the velocity of the railroad car?Use this information to answer the next 2 questions: A railroad...

What will happen to the momentum of the car as sand is loaded onto it? & What will happen to the velocity of the railroad car?

Use this information to answer the next 2 questions: A railroad car runs under a funnel that loads sand onto the car as it moves.

 

What will happen to the momentum of the car as sand is loaded onto it? (I think it is either B or C) 

a. It is impossible to determine the effect on momentum from the information given.

b. The momentum will increase because of the added mass

c. The momentum will stay the same. The extra mass will be compensated for by the loss of velocity

d. The momentum will decrease because the car will move more slowly.


What will happen to the velocity of the railroad car? (I think it is C or D) 
 
a.The velocity will decrease because of the increased mass.
b.It is impossible to predict the effect on the velocity from the information given.
c.The velocity will increase to compensate for the added mass.
d.The velocity will remain the same as the car is loaded with sand.

Please help! :) 

2 Answers | Add Yours

rohanbaishya's profile pic

Posted on

Momentum is always conserved!

Momentum is defined as mass multiplied by velocity. If sand were to fill a moving railroad car, as momentum is conserved, the car would gain mass in the form of sand, but would lose velocity as the added mass of sand slows it down.

Since mass increases by the same ratio that velocity decreases at in the example, momentum is conserved.

Hence the answer to the first question is

c. The momentum will stay the same. The extra mass will be compensated for by the loss of velocity

The answer to the second question is

a.The velocity will decrease because of the increased mass.

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