A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 one year ago
Two hard steel balls collide in a perfectly elastic collision. The first ball has a mass of 1kg and is traveling at 5m/s east. The second ball has a mass of 2kg and is initially traveling at 7 m/s west along the same path so they collide head on. After the collision the second ball is traveling at 1m/s east. What is the velocity of the 1st ball after the collision?
**How do I solve and show the work for this? :/ Thanks!!
anonymous
 one year ago
Two hard steel balls collide in a perfectly elastic collision. The first ball has a mass of 1kg and is traveling at 5m/s east. The second ball has a mass of 2kg and is initially traveling at 7 m/s west along the same path so they collide head on. After the collision the second ball is traveling at 1m/s east. What is the velocity of the 1st ball after the collision? **How do I solve and show the work for this? :/ Thanks!!

This Question is Closed

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2here we have to apply the law of conservation of total momentum and the law of conservation of kinetic energy, since the collision is elastic

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2the situation, before collision is: dw:1433610623171:dw

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2so, total momentum is: \[\Large {m_1}{v_1}  {m_2}{v_2} = 1 \times 5  2 \times 7 = ...\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0ok! so we get 514? = 9 ?

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2minus sign, means that the vector of the resultant momentum is oriented towards west

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0ohh okay! so 9, meaning 9 m/s to the west is the velocity of the 1st ball after collision?

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2no, 9 is the magnitude and sign of the resultant momentum

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0ohh okay! so it's like this? 514=9 =resultant momentum ?

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2yes! now total kinetic energy is: \[\large KE = \frac{1}{2}{m_1}v_1^2 + \frac{1}{2}{m_2}v_2^2 = \frac{1}{2} \times 1 \times 25 + \frac{1}{2} \times 2 \times 49 = ...\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0ok! so we get this? 61.5 ?

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2now let's consider the situation after the collision

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0ohhh so 61.5 is just the KE right? so we solve for velocity now? :/

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2dw:1433611229406:dw

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2no, we have to apply the conservation of total momentum first

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0oh ok! how do we do that?

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2I call with u the speed of the first ball after collision

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2so we can write: conservation of total momentum: \[\Large \begin{gathered} {m_1}u + {m_2}v{'_2} =  9 \hfill \\ 1 \times u + 7 \times 1 =  9 \hfill \\ \end{gathered} \]

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2in my reasoning i have considered positive velocity if the velocity is towards east, and negative velocity if that velocity is towards west

Michele_Laino
 one year ago
Best ResponseYou've already chosen the best response.2correct! that means the first ball, after the collision is goinf towards west

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0ahh so that is our solution? :O
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.