Work and Energy Problem

  • Thread starter iaberrant
  • Start date
  • #1
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Homework Statement



Some gliders are launched from the ground by means of a winch, which rapidly reels in a towing cable attached to the glider. What average power must the winch supply in order to accelerate a 189-kg ultralight glider from rest to 20.5 m/s over a horizontal distance of 52.2 m? Assume that friction and air resistance are negligible, and that the tension in the winch cable is constant.

Homework Equations



the formula for power = Work/ time
the formula for work = force x distance

The Attempt at a Solution



work= force x distance
= 189 x 9.8 x 52.2
=96684.84

then to find power= 96684.84 / time ?
do I use the velocity to find the time?
so it would be t= 52.2m/20.5 m/s
= 2.54 seconds?

is this correct? i'm confused as how to do this
 

Answers and Replies

  • #2
125
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The winch pulls the glider horizontally, so don't use formulas for potential energy, as that won't change. The only thing changing for the glider is its kinetic energy. Use that to find work.
 

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