The concepts in this problem are similar to those inMultiple-Concept Example 4, except that the force doing the work inthis problem is the tension in the cable. A rescue helicopter liftsa 85.5-kg person straight up by means of a cable. The person has anupward acceleration of 0.726 m/s2 and is lifted fromrest through a distance of 9.68 m. (a) What is thetension in the cable? How much work is done by (b)the tension in the cable and (c) the person'sweight? (d) Use the work-energy theorem and findthe final speed of the person. These are the correct answers to the other parts.... A.) 899.9 N B.) 8711.7 J C.) -8110.9 J The concepts in this problem are similar to those inMultiple-Concept Example 4, except that the force doing the work inthis problem is the tension in the cable. A rescue helicopter liftsa 85.5-kg person straight up by means of a cable. The person has anupward acceleration of 0.726 m/s2 and is lifted fromrest through a distance of 9.68 m. (a) What is thetension in the cable? How much work is done by (b)the tension in the cable and (c) the person'sweight? (d) Use the work-energy theorem and findthe final speed of the person. These are the correct answers to the other parts.... A.) 899.9 N B.) 8711.7 J C.) -8110.9 J
Explanation / Answer
from work energy theorem , work done = change inkineticenergy maS = ( 1/ 2) m [ v ^2 - u ^ 2 ] from this equation v = [ u ^ 2 +2aS ] Initial speed u = 0 So, v = [2aS ] =[ 2 * 0.726 * 9.68 ] = 3.749m / s