Work Done by Force F: bx^3 over \Deltax=2.6m

AI Thread Summary
The discussion revolves around calculating the work done by a variable force F = bx^3 as it moves an object from x = 0.0 m to x = 2.6 m, with b given as 3.7 N/m³. A participant initially misunderstands the formula for work, thinking it is simply force times displacement. However, it is clarified that for variable forces, the correct approach involves integrating the expression dW = F_x dx to find total work. This correction helps the participant realize their oversight and leads to a resolution of their confusion. Understanding the need for integration in variable force scenarios is crucial for solving such problems.
JasonPF
Messages
2
Reaction score
0

Homework Statement



A force F = bx^{3} acts in the x-direction. How much work is done by this force in moving an object
from x = 0.0 m to x = 2.6 m? The value of b is 3.7 N/m3.

\Deltax = 2.6m


Homework Equations


W = F\Deltax
F = bx^{3}


The Attempt at a Solution


I have no attempted solutions to this problem. I feel as if I simply am overlooking something very simple. I'm not necessarily looking for an answer, but perhaps someone could point out a concept I may have missed or not shown here that would spark my brain into solving it.

Any help is greatly appreciated.
 
Physics news on Phys.org
You have the wrong relevant equation for work. When the force doing work is variable, work is not just "force times displacement." The correct equation for an element of work in one dimension is

dW=F_xdx

To get the total work you must integrate this expression.
 
Thank you very much, as I thought, I was just over looking something. That solved my problem.
 
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