some0ne

have a look here: physicsforums com/showthread.php?s=7ff50c016352c4bdec599201ad9df2cf&p=4628168#post4628168 I'm stuck with time too

I used the W-E theorem too,basically: -> Potential Energy became Kinetic Energy at the end of the track -> in the collision no energy is lost as it is stated by the problem, so -> it is KE = Work F_spring + Work F_friction -> they both change with x so i...

sorry I told you wrong for c)... if friction and spring are the same, given friction static and kinetic coefficient is the same, it will move back

@ Pete if spring force and friction force are the same won't the masss stay put at x1?

Indeed, period formula is 2pi/w but how much of the period you need? It depends on your data, if the block stay put at x1 you need only 1/4 of period, if the block comes back you need more

for c) it depends on your value! if your spring and friction force are the same the block stays put, otherwise no!