Saturday
February 13, 2016

# Homework Help: physics

Posted by Mike on Wednesday, June 29, 2005 at 3:07pm.

When a ball falls down from a height h, its P.E is transformed into K.E as it's free-falling, BUT.....

wot abt objects not falling freely?
So...
What happens to the potential energy of an aeroplane when it lands, does it change to K.E (well it already has tht, doesn't it?) + how can the P.E change to kinetic energy when the speed is controlled by the pilot n is decreasing?

SUMONE EXPLAIN PLSSSSSSSSSSS!

When a plane lands, its kinetic energy and potential energy both decrease. The lost energy becomes mostly eddy turbulent kinetic energy heating of the air. A small fraction goes into skin heating as well. This aerodynamic heating takes place at an increased rate (compared to air heating at cruising altitude), due to the use of air flaps, thrust reversers and the fact that there is a higher air density near the ground.

In this case according to Work-Energy theorem we get the following energy equation:
K.E + P.E = Work done by engine

Hope this help:
ken@mv.ru

Kinetic energy is a function of velocity squared while potential energy is a function of height above a plane of reference. Since a landing airplane reduces its velocity to zero, its kinetic energy reduces to zero. Once landed, its potential energy relative to the ground is also zero.