Can't find mistake on Spring/block Energy problem

  • Thread starter Thread starter falco451
  • Start date Start date
  • Tags Tags
    Energy Mistake
AI Thread Summary
The discussion centers on a physics problem involving a block on an incline connected to a spring. The block, weighing 1.93 kg and positioned on a 38.2-degree incline, moves 10.9 cm down before stopping. The user attempts to calculate the coefficient of kinetic friction (μk) using work-energy principles but repeatedly arrives at an incorrect answer of approximately 0.444. Despite recalculating, the user remains uncertain about the mistake in their approach. Assistance is sought to identify the error in their calculations.
falco451
Messages
3
Reaction score
0

Homework Statement



A 1.93 kg block situated on a rough incline with 38.2 angle is connected to a spring of negligible mass having a spring constant of 90 N/m.
The block is released from rest when the spring is unstretched, and the pulley is frictionless. The block moves 10.9 cm down the incline before coming to rest.

Homework Equations



W = (fk cos 180)
x= -\muk(mg cos theta)
Wnc = ( KE + PEg + PE s)f - (KE + PEg + PEs)i


The Attempt at a Solution



I used the equations and combined them to get:
-\muk(18.194N cos 38.2) (.109) = 0 + (18.194)(-.109sin 38.2)
+ .5(90 N/m)(.109^2)

For my answer I got \muk = .4438645593
It says that my answer is wrong and I can't find what I did wrong. I recalculated several times and still got the same answer. Can you help me? Thank you!
 
Physics news on Phys.org
I retried calculating, and I got a different answer that was close to the one I had already gotten, but it was still wrong.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top