Asked by Catherine

A suitcase of weight mg = 450 is being pulled by a small strap across a level floor. The coefficient of kinetic friction between the suitcase and the floor =0.640

a) Find the optimal angle of the strap above the horizontal. (The optimal angle minimizes the force necessary to pull the suitcase at constant speed.)
Answered by Catherine
My answer is 32.6...is that right? If not please tell me how you did it...
Answered by Catherine
Oh my answer is right... can someone tell me how to calculate the minimum tension in the strap needed to pull the suitcase at constant speed? My answer for the tension is 534N and I know it's wrong...
Answered by Catherine
Please
Answered by bobpursley
well, if you are pulling at an angle of 32.6 deg...

for constant velocity, the horizontal force =friction force

friction force=(mg-upwardforce)mu
= (450-tension*sin32.4)mu
that has to equal horizontal force, or
horizontalforce= tension*cos32.4

set them equal

tension*cos32.4=450*mu-tension*sin32.4

tension= 450mu/(cosT-sinT)

solve for tension.
Answered by Maryam
How did you get the angle?
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