Question
Imagine that a person is seated in a chair that is suspended by a rope that goes over a pulley. The person holds the other end of the rope in his or her hands. Assume that the combined mass of the person and chair is M.
What is the magnitude of the downward force the person must exert on the rope to raise the chair at a constant speed? Express your answer in terms of M and g. (Hint: the answer is not Mg!)
What is the magnitude of the required force if the person is accelerating upward with mag(a ⃑)=0.10g? 
What is the magnitude of the downward force the person must exert on the rope to raise the chair at a constant speed? Express your answer in terms of M and g. (Hint: the answer is not Mg!)
What is the magnitude of the required force if the person is accelerating upward with mag(a ⃑)=0.10g? 
Answers
The tension in the rope acts upwards with respect to the chair and upwards with respect to the force of the man's hands. Both tension forces are equal and in the same direction. Ma=-Mg+tension1+tension2. Tension 1 and 2 are equal so the equation reads Ma=-Mg+2tension so Ma+Mg=2F(t) so M(a+g)/2=F. The chair moves at a constant speed so acceleration is zero implying 1/2(Mg)=F(t).
Related Questions
The combined mass of a man and a chair suspended at the midpoint of a rope of negligible mass is 50...
an object weighing 200 lbs. and suspended by a rope A is pulled asisde by the horizontal rope B and...
an object weighing 303N and suspended by rope A is pulled aside by the horizontal rope B makes an an...
A uniform horizontal beam 300N 5m long is suspended vertical from its two end by a rope, if a 600N...