7. ssm mmh The drawing shows a plane diving toward the ground and then climbing back upward. During each of these motions, the lift force  acts perpendicular to the displacement , which has the same magnitude, 1.7 x 103 m, in each case. The engines of the plane exert a thrust , which points in the direction of the displacement and has the same magnitude during the dive and the climb. The weight  of the plane has a magnitude of 5.9 x 104 N. In both motions, net work is performed due to the combined action of the forces ,  , and . (a) Is more net work done during the dive or the climb? Explain. (b) Find the difference between the net work done during the dive and the climb.

 

 

Since Lift is perpendicular to displacement, the work done by lift is zero both dive and climb.  The thrust is parallel to displacement, so the work done by thrust is the same both dive and climb.  The work done by weight however, has a component in the direction of the displacement in the dive and the component is in the opposite direction of the displacement in the climb.  So the work for the dive is positive and the work for the climb is negative for the work done by weight.  Therefore the net work is greater for the dive than the climb!

 

The difference in the net work is therefore the difference in the work done by the weight between the dive and the climb.

 

 

 

 

 

 

 

 

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This page last updated on January 11, 2020