Physics Homework Help: 3-Part Problem with Mass, Friction, and Spring Forces

AI Thread Summary
The discussion revolves around a three-part physics problem involving a 9 kg mass, friction, and spring forces. The user struggles to understand how to approach the problem, which requires calculating the compressed distance of the spring, the final speed of the mass, and the distance where the mass comes to rest. Key concepts include the initial kinetic energy of the mass, energy lost to friction, and energy stored in the spring, leading to a quadratic equation for the compressed distance. The user expresses a need for assistance due to personal circumstances affecting their studies. Overall, the thread emphasizes the importance of showing work to receive help in solving physics problems.
stacerho
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I am having trouble understanding how to work this 3 part problem.



A 9 kg mass slides to the right on a surface having a coefficient of friction 0.34. The mass has a speed of 4 m/s when contact is made with a spring that has a spring constant 159 N/m. the mass comes to rest after the spring has been compressed a distance d. The mass is then forced toward the left by the spring and continues to move in that direction beyond the outstretched position. Finally the mass comes to rest a distance D to the left of the unstretched spring. The acceleration of gravity is 9.8 m/s^2.

Part 1) Find the compressed distance d. Answer in units of m

Part 2) Find the speed vfinal at the spring’s unstretched position when the mass is moving to the left. Answer in units of m/s

Part 3) Find the distance D where the mass comes to rest. Answer in units of m.
 
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In order to get help you MUST show your work!
 
I don't have a clue, I've been so lost in this class from the beginning. I cannot even figure out where to start and that's the problem. I just need to pass this class. I'm having a baby in a few weeks and just have had so much trouble grasping this stuff.
 
Under the circumstances, I'll try and show you how to approach this, but you must make some effort yourself.

This one of those energy and work problems with a before and after state.

At the beginning the energy in the system is the KE of the mass. There's a simple formula for that. After the block stops moving the first time, the energy it used to have has gone into frictional loss and the spring.

If the block moved distance d before stopping, the work ( energy) lost to friction is mgdc where c is the coefficient of friction. The energy in the spring is Kd^2 where K is the spring constant.

If you equate the initial and final energies you get a quadratic equation in d which is a piece of cake to solve.
 
I am very confused about a question about sound waves. I am confused about the given. If the given is not in the question then how do you figure it out.
 
Yes that's the problem thank you
 

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