View Full Version : physics homework: sliding masses, springs, tracks, etc

04-04-2007, 03:46 PM
Hi I'm really looking to just get answers on these questions: If anyone is willing to help by just giving me the answers, i'm at the point where I just want to get throug this, i'm having a baby in a couple of weeks and no longer have the ability to get this stuff completed. If you can help that would be great.

1) 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.

2) The surfaces are frictionless. The tracks are 60degrees from horizontal. A 350 kg mass is released from rest on a track at a height 3.2 m above a horizontal surface at the foot of the slope. It collides elastically with a 468 kg mass initially at rest on the horizontal surface. The mass 468 kg slides up a similar track. The acceleration of gravity is 9.8m/s^2.

Part 1) What is the speed of the block 468 kg immediately after the collision? Answer in units of m/s.

Part 2) To what maximum height h2 above the horizontal surface will the mass 468 kg slide? Answer in units of m.

3) A body oscillates with simple harmonic motion along the x-axis. Its displacement varies with the time according to the equation A=A sin (wt+ pi/3)

Where w=pi radians per second, t is in seconds, and a= 7.6m.
What is the phase of motion at t=2.6s? Answer in units of rad.

04-04-2007, 06:35 PM
1) Can you use this thread (http://www.freemathhelp.com/forum/viewtopic.php?t=21075) to get started?

2) Can you use the reply on this related thread (http://www.freemathhelp.com/forum/viewtopic.php?t=22186) to get started?

3) Without a definition of "phase of motion", reposting (http://www.freemathhelp.com/forum/viewtopic.php?t=22185) this question is unlikely to result in any different answer than before.

Note: A physics forum (http://www.physicsforums.com/) might be more appropriate for physics questions, and you might receive more timely replies.

Thank you.