Question
I need help with the following problem. A mass Ma is resting on a horizontal frictional surface. Amassless, stretchless cord is then attached to the right face ofthis mass, extending to the right and passing over a massless,frictionless pulley. The cord then extends downward at an angle ofdepression of (between 0 degrees and 90 degrees) and isattached to a mass Mb which is sitting on a frictional planeinclined downward towards the right also at an angle of withrespect to the horizontal. There is tension in the cord. I would like to know how could I calculate the mass needed inmass Mb (as a percentage of mass Ma) so that mass Ma is just aboutto start to move. And then I have to find how to calculate theaccelaration of mass Ma as it starts to move. As you can see, this problem has no units of mass orcoefficients of static friction or kinetic friction and would likesome help Thank you. I need help with the following problem. A mass Ma is resting on a horizontal frictional surface. Amassless, stretchless cord is then attached to the right face ofthis mass, extending to the right and passing over a massless,frictionless pulley. The cord then extends downward at an angle ofdepression of (between 0 degrees and 90 degrees) and isattached to a mass Mb which is sitting on a frictional planeinclined downward towards the right also at an angle of withrespect to the horizontal. There is tension in the cord. I would like to know how could I calculate the mass needed inmass Mb (as a percentage of mass Ma) so that mass Ma is just aboutto start to move. And then I have to find how to calculate theaccelaration of mass Ma as it starts to move. As you can see, this problem has no units of mass orcoefficients of static friction or kinetic friction and would likesome help Thank you.
Explanation / Answer
let the coefficient of friction be and let us assume that the coefficient of friction between any twosurfaces is the same then we need to have for the limiting case we have mbgsin=mbgcos+mag solve for we know ,ma and mb