### Subject: How can energy be lost during energy conversions?

Date: Thu Oct 8 09:48:35 2009
Posted by Emily
Grade level: 10-12 School: No school entered.
City: No city entered. State/Province: No state entered. Country: England
Area of science: Physics
ID: 1255020515.Ph
Message:
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At school I did a simple classroom experiment to demonstrate how gravitational
potential energy is converted into kinetic energy when a dynamics trolley of a
certain mass is released from the top of a ramp. The speed of the dynamics
trolley as it moved down the ramp was detected using speed sensors. After
completing the experiment I did some calculations to determine the
gravitational potential energy of the trolley at the start of the experiment
(at the top of the ramp before being released) and the kinetic energy it had
as it passed through the speed sensors. I then used these 2 figures to work
out the efficiency of the transfer of gravitational potential energy into
kinetic energy. I found from my calculations that the conversion was not 100%
efficient. My question is, how was energy lost during this conversion? Was
this energy lost due to friction between the wheels of the dynamics trolley
and surface of the ramp? If this is the case, was this energy lost in the form
of heat energy? Did this friction cause both the wheels of the trolley and the
surface of the ramp to gain heat (or just one of the aforementioned)? Where
does this heat energy then go - is it simply lost to the surroundings or can
it somehow be usefully reused/recycled? I also wonder whether energy could
have been lost during the conversion of gravitational potential energy into
kinetic energy due to air resistance? I believe that air resistance can reduce
the speed of a moving object (thus it is useful to streamline the shape of a
racing car) but am unsure whether this effectively reduces its amount of
kinetic energy. Would one or both of these factors (+ any others) be
responsible for the inefficient conversion of gravitational potential energy
into kinetic energy? If, in fact, air resistance is also a reason for energy
loss, what happens to this lost energy? Is it perhaps lost as heat energy and
warms the surroundings? Thank you

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Re: How can energy be lost during energy conversions?

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