Collision of marbles and stones

[strawberry923]

1. Question: A 100g stone rests on a fricionless horizontal surface. A marble of mass 40g, traveling horizontantally at 30m/s strikes the stone and rebunds horizontally at right angles to its original direction wiht a speed of 20m/s. What is the velocity (magnitude and direction) of the stone after it has been struck? Can you see anything wrong with this question?



i think the relevant equations are: p = final momentum - initial momentum which is here 1,2 + 0,8 = 2 kgm/s



and to look for the velocity after it has been struck i used the formula p= 2kgm/s= (mA+mB).v so the v= 2:0,14 = 14,29, but think that's not the right formula and i don't know what's wrong with this question, i think its the "at right angles" bit, that confuses me the most... can someone pleaase help? :)

 

[anathema]

Hello there,

I can see a few potential issues with this question.

Firstly, the given information is not enough to calculate the velocity of the stone after it has been struck. We do not know the initial velocity of the stone, which is needed to calculate the final velocity using the equation p = mv. We also do not know the angle at which the marble strikes the stone, which would affect the direction of the stone's velocity after the collision.

Secondly, the equation used to calculate the velocity after the collision is incorrect. The correct equation to use is conservation of momentum, which states that the total momentum before the collision is equal to the total momentum after the collision. This can be expressed as m1v1 + m2v2 = m1v1' + m2v2', where m1 and m2 are the masses of the objects and v1, v2, v1', and v2' are their velocities before and after the collision, respectively.

Lastly, the statement "rebounds horizontally at right angles to its original direction" is unclear. It is not specified whether the original direction refers to the direction of the marble's velocity or the direction of the stone's velocity. This ambiguity can affect the calculation of the final velocity of the stone.

To accurately solve this problem, we would need to know the initial velocity and angle of the marble, as well as the initial velocity and angle of the stone. Without this information, it is not possible to determine the final velocity of the stone after the collision.

I hope this helps clarify any confusion. If you have any further questions, please let me know.