minoupak

I thought I had the concept down, but I thought wrong....I seem to be missing a step or my algebra is wrong...please someone tell me what I'm doing wrong? A block of mass (m=12kg) is released from rest on a frictionless incline of an angle (30 degrees). Below the block is a spring which can be compressed .02meters by a force of 270N. The block momentarily stops when it compresses the spring by 0.055m. How far does the block move down the inline from its rest position to this stopping point? and the speed of the block just as it touches the spring. Ok since there are only conservative forces, the equation should be Kinetic(f)+Potential Energies(f) = Kinetic energy (i) + Potential Energies (i). I got stuck from the beginning when I was trying to find out the spring rate...which should just be 1/2*k*x^2...equaling 270N when x=0.02. But then I get spring rating of 1350000N! something's wrong there...then I thought maybe 270N was the work, but the numbers are still wrong...please someone help! thanks!

haha yeah i eventually figured out that coefficient of friction was negative. Thanks for the second problem! I didn't know where to start the problem from. That helps alot

just to let everyone know that i'm not shamming....lol this is what i have for the first problem: @=theta.. U=coefficient of kinetic friction in the x-dir FCos@-WSin@+UN=ma in the y-dir N-FSin@+WCos@=ma N=FSin@+WCos@ So the equation by substituting N would be: FCos@-WSin@+U(FSin@+WCos@)=ma and acceleration according to this would just be all that divided by m....but something must be off bcuz that's not the correct answer...:) btw, the acceleration should be 2.1 m/s*s please someone tell me what is wrong with my equation? lol i'm desperate to know what i don't understand

Aghhh....i think I've finally crashed...i can't seem to figure a problem out...actually two please anyone help? 1. A 5.0 kg block is sent sliding up a plane inclined at 37 degrees while horizontal force F of magnitude 50N acts on it. The coefficient of kinetic friction is .30. a) magnitude of the block's acceleration Ok i know the direction of the acceleration is down the incline...but i'm really stuck on the equation to find the acceleration.... 2. A 1.34kg ball is connected by means of two massless strings, each of length L=1.7m to a vertical, rotating rod. The strings are tied to the rod with separation of d=1.70 m and are taut. The tension in the upper string is 35N. a) the tension in the lower string, :) the magnitude of the net string force on the ball c) speed of the ball I can get c, if i can get a)...

Hi all, i guess i have to post here first before I get any help or give comments...I think i'll be visiting here a lot since I picked Mech Engineering as a major...later